diff --git a/test/ripper/test_parser_events.rb b/test/ripper/test_parser_events.rb
index 8b835d3377b..07234f4d692 100644
--- a/test/ripper/test_parser_events.rb
+++ b/test/ripper/test_parser_events.rb
@@ -1752,7 +1752,7 @@ class TestRipper::ParserEvents < Test::Unit::TestCase
   end
 
   def test_return_out_of_compile_error_no_memory_leak
-    assert_no_memory_leak(%w(-rripper), "#{<<~'begin;'}", "#{<<~'end;'}", rss: true)
+    assert_no_memory_leak(%w(-rripper), "#{<<~'begin;'}", "#{<<~'end;'}", rss: true, samples: 10..100)
       class MyRipper < Ripper
         def initialize(src, &blk)
           super(src)
@@ -1767,14 +1767,14 @@ class TestRipper::ParserEvents < Test::Unit::TestCase
       # Check that call_parse does return a syntax error
       raise "call_parse should return a syntax error" unless call_parse
     begin;
-      100_000.times do
+      1_000.times do
         call_parse
       end
     end;
   end
 
-  def test_return_out_of_warn_no_memory_leak
-    assert_no_memory_leak(%w(-rripper), "#{<<~'begin;'}", "#{<<~'end;'}", rss: true)
+  def test_return_out_of_warn_dup_keys_no_memory_leak
+    assert_no_memory_leak(%w(-rripper), "#{<<~'begin;'}", "#{<<~'end;'}", rss: true, samples: 10..100)
       class MyRipper < Ripper
         def initialize(src, &blk)
           super(src)
@@ -1789,12 +1789,14 @@ class TestRipper::ParserEvents < Test::Unit::TestCase
       # Check that call_parse does warn
       raise "call_parse should warn" unless call_parse
     begin;
-      500_000.times do
+      1_000.times do
         call_parse
       end
     end;
+  end
 
-    assert_no_memory_leak(%w(-rripper), "#{<<~'begin;'}", "#{<<~'end;'}", rss: true)
+  def test_return_out_of_warn_token_info_no_memory_leak
+    assert_no_memory_leak(%w(-rripper), "#{<<~'begin;'}", "#{<<~'end;'}", rss: true, samples: 10..100)
       class MyRipper < Ripper
         def initialize(src, &blk)
           super(src)
@@ -1810,7 +1812,7 @@ class TestRipper::ParserEvents < Test::Unit::TestCase
       # Check that call_parse does warn
       raise "call_parse should warn" unless call_parse
     begin;
-      1_000_000.times do
+      1_000.times do
         call_parse
       end
     end;
diff --git a/test/ripper/test_ripper.rb b/test/ripper/test_ripper.rb
index 4baca69b57d..652766b13ad 100644
--- a/test/ripper/test_ripper.rb
+++ b/test/ripper/test_ripper.rb
@@ -167,41 +167,52 @@ end
     assert_empty(lex)
   end
 
-  def test_no_memory_leak
-    assert_no_memory_leak(%w(-rripper), "", "#{<<~'end;'}", rss: true)
-      2_000_000.times do
+  def test_empty_no_memory_leak
+    assert_no_memory_leak(%w(-rripper), "", "#{<<-"{#"}\n#{<<-'};'}", rss: true, samples: 2..100)
+    {#
+      1000.times do
         Ripper.parse("")
       end
-    end;
+    };
+  end
 
+  def test_unclosed_class_no_memory_leak
     # [Bug #19835]
-    assert_no_memory_leak(%w(-rripper), "", "#{<<~'end;'}", rss: true)
-      1_000_000.times do
+    assert_no_memory_leak(%w(-rripper), "", "#{<<-"{#"}\n#{<<-'};'}", rss: true, samples: 2..100)
+    {#
+      1000.times do
         Ripper.parse("class Foo")
       end
-    end;
+    };
+  end
 
+  def test_unclosed_lambda_no_memory_leak
     # [Bug #19836]
-    assert_no_memory_leak(%w(-rripper), "", "#{<<~'end;'}", rss: true)
-      1_000_000.times do
+    assert_no_memory_leak(%w(-rripper), "", "#{<<-"{#"}\n#{<<-'};'}", rss: true, samples: 2..100)
+    {#
+      1000.times do
         Ripper.parse("-> {")
       end
-    end;
+    };
+  end
 
+  def test_lambda_it_no_memory_leak
     # [Bug #21004]
-    assert_no_memory_leak(%w(-rripper), "", <<~RUBY, rss: true)
-      1_000_000.times do
+    assert_no_memory_leak(%w(-rripper), "", "#{<<-"{#"}\n#{<<-'};'}", rss: true, samples: 2..100)
+    {#
+      1000.times do
         Ripper.parse("-> do it end")
       end
-    RUBY
+    };
   end
 
   def test_sexp_no_memory_leak
-    assert_no_memory_leak(%w(-rripper), "", "#{<<~'end;'}", rss: true)
-      1_000_000.times do
+    assert_no_memory_leak(%w(-rripper), "", "#{<<-"{#"}\n#{<<-'};'}", rss: true, samples: 2..100)
+    {#
+      1000.times do
         Ripper.sexp("")
       end
-    end;
+    };
   end
 
   class TestInput < self
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index ea3007389c7..9691de54342 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -2058,11 +2058,10 @@ class TestArray < Test::Unit::TestCase
 
   def test_short_heap_array_sort_bang_memory_leak
     bug11332 = '[ruby-dev:49166] [Bug #11332]'
-    assert_no_memory_leak([], <<-PREP, <<-TEST, bug11332, limit: 1.3, timeout: 60)
+    assert_no_memory_leak([], <<-PREP, <<-TEST, bug11332, limit: 1.3, timeout: 60, samples: 2..100)
       def t; ary = [*1..5]; ary.pop(2); ary.sort!; end
-      1.times {t}
     PREP
-      500000.times {t}
+      5_000.times {t}
     TEST
   end
 
diff --git a/test/ruby/test_ast.rb b/test/ruby/test_ast.rb
index 5b3adefe5cf..0146f9b3cc8 100644
--- a/test/ruby/test_ast.rb
+++ b/test/ruby/test_ast.rb
@@ -346,14 +346,13 @@ class TestAst < Test::Unit::TestCase
 
   def test_invalid_yield_no_memory_leak
     # [Bug #21383]
-    assert_no_memory_leak([], "#{<<-"begin;"}", "#{<<-'end;'}", rss: true)
+    assert_no_memory_leak([], "#{<<-"begin;"}", "#{<<-'end;'}", rss: true, samples: 2..100)
       code = proc do
         eval("class C; yield; end")
       rescue SyntaxError
       end
-      1_000.times(&code)
     begin;
-      100_000.times(&code)
+      200.times(&code)
     end;
   end
 
diff --git a/test/ruby/test_class.rb b/test/ruby/test_class.rb
index a5d715c47a7..990b0ccac3d 100644
--- a/test/ruby/test_class.rb
+++ b/test/ruby/test_class.rb
@@ -928,12 +928,7 @@ class TestClass < Test::Unit::TestCase
   end
 
   def test_classext_memory_leak
-    assert_no_memory_leak([], <<-PREP, <<-CODE, rss: true)
-code = proc { Class.new }
-1_000.times(&code)
-PREP
-3_000_000.times(&code)
-CODE
+    assert_no_memory_leak([], "", "30_000.times {Class.new}", rss: true, samples: 2..100)
   end
 
   def test_instance_freeze_dont_freeze_the_class_bug_19164
diff --git a/test/ruby/test_eval.rb b/test/ruby/test_eval.rb
index b880b03e08f..7f4a983e6b8 100644
--- a/test/ruby/test_eval.rb
+++ b/test/ruby/test_eval.rb
@@ -614,9 +614,9 @@ class TestEval < Test::Unit::TestCase
   end
 
   def test_syntax_error_no_memory_leak
-    assert_no_memory_leak([], "#{<<~'begin;'}", "#{<<~'end;'}", rss: true)
+    assert_no_memory_leak([], "#{<<~'begin;'}", "#{<<~'end;'}", rss: true, samples: 5)
     begin;
-      100_000.times do
+      20_000.times do
         eval("/[/=~s")
       rescue SyntaxError
       else
diff --git a/test/ruby/test_hash.rb b/test/ruby/test_hash.rb
index e797aaf771c..f6bdadf37bb 100644
--- a/test/ruby/test_hash.rb
+++ b/test/ruby/test_hash.rb
@@ -179,9 +179,9 @@ class TestHash < Test::Unit::TestCase
   end
 
   def test_st_literal_memory_leak
-    assert_no_memory_leak([], "", "#{<<~"begin;"}\n#{<<~'end;'}", rss: true)
+    assert_no_memory_leak([], "", "#{<<~"begin;"}\n#{<<~'end;'}", rss: true, samples: 5)
     begin;
-      1_000_000.times do
+      200_000.times do
         # >8 element hashes are ST allocated rather than AR allocated
         {a: 1, b: 2, c: 3, d: 4, e: 5, f: 6, g: 7, h: 8, i: 9}
       end
@@ -1523,10 +1523,10 @@ class TestHash < Test::Unit::TestCase
   end
 
   def test_compare_by_identy_memory_leak
-    assert_no_memory_leak([], "", "#{<<~"begin;"}\n#{<<~'end;'}", "[Bug #20145]", rss: true)
+    assert_no_memory_leak([], "", "#{<<~"begin;"}\n#{<<~'end;'}", "[Bug #20145]", rss: true, samples: 5)
     begin;
       h = { 1 => 2 }.compare_by_identity
-      1_000_000.times do
+      200_000.times do
         h.select { false }
       end
     end;
@@ -1995,9 +1995,9 @@ class TestHashOnly < Test::Unit::TestCase
   end
 
   def test_st_literal_memory_leak
-    assert_no_memory_leak([], "", "#{<<~"begin;"}\n#{<<~'end;'}", rss: true)
+    assert_no_memory_leak([], "", "#{<<~"begin;"}\n#{<<~'end;'}", rss: true, samples: 5)
     begin;
-      1_000_000.times do
+      200_000.times do
         # >8 element hashes are ST allocated rather than AR allocated
         {a: 1, b: 2, c: 3, d: 4, e: 5, f: 6, g: 7, h: 8, i: 9}
       end
@@ -2096,17 +2096,14 @@ class TestHashOnly < Test::Unit::TestCase
   end
 
   def test_rehash_memory_leak
-    assert_no_memory_leak([], <<~PREP, <<~CODE, rss: true)
+    assert_no_memory_leak([], <<~PREP, <<~CODE, rss: true, samples: 2..100)
       ar_hash = 1.times.map { |i| [i, i] }.to_h
       st_hash = 10.times.map { |i| [i, i] }.to_h
-
-      code = proc do
+    PREP
+      10_000.times do
         ar_hash.rehash
         st_hash.rehash
       end
-      1_000.times(&code)
-    PREP
-      1_000_000.times(&code)
     CODE
   end
 
@@ -2172,11 +2169,10 @@ class TestHashOnly < Test::Unit::TestCase
   end
 
   def test_replace_memory_leak
-    assert_no_memory_leak([], "#{<<-"begin;"}", "#{<<-'end;'}", rss: true)
+    assert_no_memory_leak([], "#{<<-"begin;"}", "#{<<-'end;'}", rss: true, samples: 2..100)
     h = ("aa".."zz").each_with_index.to_h
-    10_000.times {h.dup}
     begin;
-      500_000.times {h.dup.replace(h)}
+      5_000.times {h.dup.replace(h)}
     end;
   end
 
diff --git a/test/ruby/test_iseq.rb b/test/ruby/test_iseq.rb
index b0eba77fb4f..d4bc38023ee 100644
--- a/test/ruby/test_iseq.rb
+++ b/test/ruby/test_iseq.rb
@@ -321,7 +321,7 @@ class TestISeq < Test::Unit::TestCase
 
   def test_invalid_source_no_memory_leak
     # [Bug #21394]
-    assert_no_memory_leak(["-rtempfile"], "#{<<-"begin;"}", "#{<<-'end;'}", rss: true)
+    assert_no_memory_leak(["-rtempfile"], "#{<<-"begin;"}", "#{<<-'end;'}", rss: true, samples: 2..100)
       code = proc do |t|
         RubyVM::InstructionSequence.new(nil)
       rescue TypeError
@@ -329,9 +329,8 @@ class TestISeq < Test::Unit::TestCase
         raise "TypeError was not raised during RubyVM::InstructionSequence.new"
       end
 
-      10.times(&code)
     begin;
-      1_000_000.times(&code)
+      10_000.times(&code)
     end;
 
     # [Bug #21394]
@@ -985,10 +984,10 @@ class TestISeq < Test::Unit::TestCase
   end
 
   def test_loading_kwargs_memory_leak
-    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~'end;'}", rss: true)
+    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~'end;'}", rss: true, samples: 5)
       a = RubyVM::InstructionSequence.compile("foo(bar: :baz)").to_binary
     begin;
-      1_000_000.times do
+      200_000.times do
         RubyVM::InstructionSequence.load_from_binary(a)
       end
     end;
diff --git a/test/ruby/test_method.rb b/test/ruby/test_method.rb
index 041de2610e3..72a0c02cbbf 100644
--- a/test/ruby/test_method.rb
+++ b/test/ruby/test_method.rb
@@ -1812,11 +1812,11 @@ class TestMethod < Test::Unit::TestCase
   end
 
   def test_kwarg_eval_memory_leak
-    assert_no_memory_leak([], "", <<~RUBY, rss: true, limit: 1.2)
+    assert_no_memory_leak([], "", <<~RUBY, rss: true, limit: 1.2, samples: 5)
       obj = Object.new
       def obj.test(**kwargs) = nil
 
-      100_000.times do
+      20_000.times do
         eval("obj.test(foo: 123)")
       end
     RUBY
diff --git a/test/ruby/test_module.rb b/test/ruby/test_module.rb
index 0b7f241325c..10d0e67e740 100644
--- a/test/ruby/test_module.rb
+++ b/test/ruby/test_module.rb
@@ -3429,23 +3429,20 @@ class TestModule < Test::Unit::TestCase
 
   def test_iclass_memory_leak
     # [Bug #19550]
-    assert_no_memory_leak([], <<~PREP, <<~CODE, rss: true)
-      code = proc do
+    assert_no_memory_leak([], "", <<~CODE, rss: true, samples: 2..30)
+      100_000.times do
         mod = Module.new
         Class.new do
           include mod
         end
       end
-      1_000.times(&code)
-    PREP
-      3_000_000.times(&code)
     CODE
   end
 
   def test_complemented_method_entry_memory_leak
     # [Bug #19894] [Bug #19896]
-    assert_no_memory_leak([], <<~PREP, <<~CODE, rss: true)
-      code = proc do
+    assert_no_memory_leak([], "", <<~CODE, rss: true, samples: 2..30)
+      10_000.times do
         $c = Class.new do
           def foo; end
         end
@@ -3465,21 +3462,15 @@ class TestModule < Test::Unit::TestCase
           end
         end.new
       end
-      1_000.times(&code)
-    PREP
-      300_000.times(&code)
     CODE
   end
 
   def test_module_clone_memory_leak
     # [Bug #19901]
-    assert_no_memory_leak([], <<~PREP, <<~CODE, rss: true)
-      code = proc do
+    assert_no_memory_leak([], "", <<~CODE, rss: true, samples: 2..100)
+      10_000.times do
         Module.new.clone
       end
-      1_000.times(&code)
-    PREP
-      1_000_000.times(&code)
     CODE
   end
 
diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb
index fd0532ef3a0..1c554d2eec5 100644
--- a/test/ruby/test_regexp.rb
+++ b/test/ruby/test_regexp.rb
@@ -1009,39 +1009,36 @@ class TestRegexp < Test::Unit::TestCase
     # partially parsed branch (parse_subexp freed the alternation list but not
     # the node parse_branch had built so far). Regexp#to_s reaches this path
     # for every /(?:a|b)c(d)/-shaped regexp.
-    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~"end;"}", "[Bug #22384]", rss: true)
+    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~"end;"}", "[Bug #22384]", rss: true, samples: 2..100)
       code = proc do
         Regexp.new("a|b(c") rescue nil
         /(?:a|b)c(d)/.to_s
       end
 
-      1_000.times(&code)
     begin;
-      300_000.times(&code)
+      3_000.times(&code)
     end;
   end
 
   def test_regsub_no_memory_leak
-    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~"end;"}", rss: true)
+    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~"end;"}", rss: true, samples: 2..100)
       code = proc do
         "aaaaaaaaaaa".gsub(/a/, "")
       end
 
-      1_000.times(&code)
     begin;
-      100_000.times(&code)
+      1_000.times(&code)
     end;
   end
 
   def test_regsub_no_memory_leak_many_captures
-    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~"end;"}", rss: true)
+    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~"end;"}", rss: true, samples: 2..100)
       code = proc do
         "aaaaaaaaaaa".gsub(/(a)(b)?(c)?(d)?(e)?(f)?(g)?(h)?/, "")
       end
 
-      1_000.times(&code)
     begin;
-      100_000.times(&code)
+      1_000.times(&code)
     end;
   end
 
@@ -2107,10 +2104,10 @@ class TestRegexp < Test::Unit::TestCase
   end
 
   def test_s_timeout_memory_leak
-    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~"end;"}", "[Bug #20228]", rss: true)
-      Regexp.timeout = 0.001
-      regex = /^(a*)*$/
-      str = "a" * 1000000 + "x"
+    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~'end;'}", "[Bug #20228]", rss: true, samples: 100..200)
+      Regexp.timeout = 0.000001
+      regex = Regexp.new("^#{"(a*)" * 10_000}x$")
+      str = "a" * 1_000_000 + "x"
 
       code = proc do
         regex =~ str
@@ -2119,7 +2116,7 @@ class TestRegexp < Test::Unit::TestCase
 
       10.times(&code)
     begin;
-      1_000.times(&code)
+      100.times(&code)
     end;
   end
 
@@ -2196,7 +2193,7 @@ class TestRegexp < Test::Unit::TestCase
   end
 
   def test_timeout_memory_leak
-    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~'end;'}", "[Bug #20650]", timeout: 100, rss: true)
+    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~'end;'}", "[Bug #20650]", rss: true, samples: 100..200)
       regex = Regexp.new("^#{"(a*)" * 10_000}x$", timeout: 0.000001)
       str = "a" * 1_000_000 + "x"
 
@@ -2207,7 +2204,7 @@ class TestRegexp < Test::Unit::TestCase
 
       10.times(&code)
     begin;
-      1_000.times(&code)
+      100.times(&code)
     end;
   end
 
diff --git a/test/ruby/test_settracefunc.rb b/test/ruby/test_settracefunc.rb
index 54819ec16d0..da50a8ff51f 100644
--- a/test/ruby/test_settracefunc.rb
+++ b/test/ruby/test_settracefunc.rb
@@ -652,12 +652,7 @@ class TestSetTraceFunc < Test::Unit::TestCase
 
   # Bug #18264
   def test_tracepoint_memory_leak
-    assert_no_memory_leak([], <<-PREP, <<-CODE, rss: true)
-code = proc { TracePoint.new(:line) { } }
-1_000.times(&code)
-PREP
-1_000_000.times(&code)
-CODE
+    assert_no_memory_leak([], "", "10_000.times {TracePoint.new(:line) { }}", rss: true, samples: 2..100)
   end
 
   def test_tracepoint_bmethod_memory_leak
diff --git a/test/ruby/test_shapes.rb b/test/ruby/test_shapes.rb
index 9d7b4a34663..ccafaf1882e 100644
--- a/test/ruby/test_shapes.rb
+++ b/test/ruby/test_shapes.rb
@@ -570,21 +570,19 @@ class TestShapes < Test::Unit::TestCase
   end
 
   def test_evacuate_generic_ivar_memory_leak
-    assert_no_memory_leak([], "#{<<~'begin;'}", "#{<<~'end;'}", rss: true)
+    assert_no_memory_leak([], "#{<<~'begin;'}", "#{<<~'end;'}", rss: true, samples: 5)
       o = []
       o.instance_variable_set(:@a, 1)
 
       RubyVM::Shape.exhaust_shapes
-
-      ary = 1_000_000.times.map { [] }
     begin;
+      ary = Array.new(200_000) { [] }
       ary.each do |o|
         o.instance_variable_set(:@a, 1)
         o.instance_variable_set(:@b, 1)
       end
       ary.clear
       ary = nil
-      GC.start
     end;
   end
 
@@ -1180,13 +1178,13 @@ class TestShapes < Test::Unit::TestCase
   end
 
   def test_duplicating_complex_objects_memory_leak
-    assert_no_memory_leak([], "#{<<~'begin;'}", "#{<<~'end;'}", "[Bug #20162]", rss: true)
+    assert_no_memory_leak([], "#{<<~'begin;'}", "#{<<~'end;'}", "[Bug #20162]", rss: true, samples: 5)
       RubyVM::Shape.exhaust_shapes
 
       o = Object.new
       o.instance_variable_set(:@a, 0)
     begin;
-      1_000_000.times do
+      200_000.times do
         o.dup
       end
     end;
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index 8a9ba355ab1..be800d66028 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -104,24 +104,18 @@ class TestString < Test::Unit::TestCase
   def test_initialize_memory_leak
     return unless @cls == String
 
-    assert_no_memory_leak([], <<-PREP, <<-CODE, rss: true)
-code = proc {('x'*100_000).__send__(:initialize, '')}
-1_000.times(&code)
-PREP
-100_000.times(&code)
-CODE
+    assert_no_memory_leak([], '', <<-CODE, rss: true, samples: 2..100)
+    1_000.times {('x'*100_000).__send__(:initialize, '')}
+    CODE
   end
 
   # Bug #18154
   def test_initialize_nofree_memory_leak
     return unless @cls == String
 
-    assert_no_memory_leak([], <<-PREP, <<-CODE, rss: true)
-code = proc {0.to_s.__send__(:initialize, capacity: 100_000)}
-1_000.times(&code)
-PREP
-100_000.times(&code)
-CODE
+    assert_no_memory_leak([], '', <<-CODE, rss: true, samples: 2..100)
+    1_000.times {0.to_s.__send__(:initialize, capacity: 100_000)}
+    CODE
   end
 
   def test_AREF # '[]'
@@ -765,12 +759,14 @@ CODE
       assert_raise(ArgumentError) {S("mypassword".encode(enc)).crypt(S("aa"))}
     end
 
-    @cls == String and
-      assert_no_memory_leak([], "s = ''; salt_proc = proc{#{(crypt_supports_des_crypt? ? '..' : good_salt).inspect}}", "#{<<~"begin;"}\n#{<<~'end;'}")
-
-    begin;
-      1000.times { s.crypt(-salt_proc.call).clear  }
-    end;
+    if @cls == String
+      assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~'end;'}", samples: 2..100)
+      s = ''
+      salt = -""#{(crypt_supports_des_crypt? ? '..' : good_salt).dump}
+      begin;
+        10.times { s.crypt(salt).clear  }
+      end;
+    end
   end
 
   def test_delete
@@ -2489,18 +2485,14 @@ CODE
   end
 
   def test_start_with_timeout_memory_leak
-    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~'end;'}", "[Bug #20653]", rss: true)
+    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~'end;'}", "[Bug #20653]", rss: true, samples: 2..100)
       regex = Regexp.new("^#{"(a*)" * 10_000}x$", timeout: 0.000001)
       str = "a" * 1_000_000 + "x"
-
-      code = proc do
+    begin;
+      10.times do
         str.start_with?(regex)
       rescue
       end
-
-      10.times(&code)
-    begin;
-      1_000.times(&code)
     end;
   end
 
@@ -4520,12 +4512,11 @@ CODE
         def fallback.[](_str) = raise MyError
       RUBY
     }.each do |type, code|
-      assert_no_memory_leak([], '', <<~RUBY, "fallback type is #{type}", rss: true)
+      assert_no_memory_leak([], <<~PREPARE, <<~RUBY, "fallback type is #{type}", rss: true, samples: 2..100)
         class MyError < StandardError; end
-
         #{code}
-
-        100_000.times do |i|
+      PREPARE
+        1000.times do |i|
           "\\ufffd".encode(Encoding::US_ASCII, fallback:)
         rescue MyError
         end
@@ -4550,12 +4541,11 @@ CODE
         def fallback.[](_str) = "\\uffee"
       RUBY
     }.each do |type, code|
-      assert_no_memory_leak([], '', <<~RUBY, "fallback type is #{type}", rss: true)
+      assert_no_memory_leak([], <<~PREPARE, <<~RUBY, "fallback type is #{type}", rss: true, samples: 2..100)
         class MyError < StandardError; end
-
         #{code}
-
-        100_000.times do |i|
+      PREPARE
+        1000.times do |i|
           "\\ufffd".encode(Encoding::US_ASCII, fallback:)
         rescue ArgumentError
         end
@@ -4580,12 +4570,11 @@ CODE
         def fallback.[](_str) = Object.new
       RUBY
     }.each do |type, code|
-      assert_no_memory_leak([], '', <<~RUBY, "fallback type is #{type}", rss: true)
+      assert_no_memory_leak([], <<~PREPARE, <<~RUBY, "fallback type is #{type}", rss: true, samples: 2..100)
         class MyError < StandardError; end
-
         #{code}
-
-        100_000.times do |i|
+      PREPARE
+        1000.times do |i|
           "\\ufffd".encode(Encoding::US_ASCII, fallback:)
         rescue TypeError
         end
diff --git a/test/ruby/test_struct.rb b/test/ruby/test_struct.rb
index 15a424932a6..54785b8b8de 100644
--- a/test/ruby/test_struct.rb
+++ b/test/ruby/test_struct.rb
@@ -548,15 +548,13 @@ module TestStruct
     omit 'skip on riscv64-linux CI machine. See https://github.com/ruby/ruby/pull/13422' if ENV['RUBY_DEBUG'] == 'ci' && /riscv64-linux/ =~ RUBY_DESCRIPTION
 
     # [Bug #20311]
-    assert_no_memory_leak([], <<~PREP, <<~CODE, rss: true, limit: 2.2)
+    assert_no_memory_leak([], <<~PREP, <<~CODE, rss: true, limit: 2.2, samples: 2..50)
       code = proc do
         Struct.new("A")
         Struct.send(:remove_const, :A)
       end
-
-      10_000.times(&code)
     PREP
-      50_000.times(&code)
+      1_000.times(&code)
     CODE
   end
 
diff --git a/test/ruby/test_syntax.rb b/test/ruby/test_syntax.rb
index ae4cdf5fe71..49500e4fd6b 100644
--- a/test/ruby/test_syntax.rb
+++ b/test/ruby/test_syntax.rb
@@ -1533,17 +1533,14 @@ eom
   end
 
   def test_invalid_symbol_in_hash_memory_leak
-    assert_no_memory_leak([], "#{<<-'begin;'}", "#{<<-'end;'}", rss: true)
+    assert_no_memory_leak([], "#{<<-'begin;'}", "#{<<-'end;'}", rss: true, samples: 2..1_000)
       str = '{"\xC3": 1}'.force_encoding("UTF-8")
-      code = proc do
+    begin;
+      1_000.times do
         eval(str)
         raise "unreachable"
       rescue SyntaxError
       end
-
-      1_000.times(&code)
-    begin;
-      1_000_000.times(&code)
     end;
   end
 
@@ -2471,16 +2468,15 @@ eom
   end
 
   def test_argument_forwarding_with_super_memory_leak
-    assert_no_memory_leak([], "#{<<-'begin;'}", "#{<<-'end;'}", rss: true)
+    assert_no_memory_leak([], "#{<<-'begin;'}", "#{<<-'end;'}", rss: true, samples: 2..100)
       code = proc do
         eval("def foo(...) super(...) {}; end")
         raise "unreachable"
       rescue SyntaxError
       end
 
-      1_000.times(&code)
     begin;
-      100_000.times(&code)
+      1_000.times(&code)
     end;
   end
 
diff --git a/test/ruby/test_weakmap.rb b/test/ruby/test_weakmap.rb
index 789a54789ac..2c65b873321 100644
--- a/test/ruby/test_weakmap.rb
+++ b/test/ruby/test_weakmap.rb
@@ -204,9 +204,9 @@ class TestWeakMap < Test::Unit::TestCase
   end
 
   def test_no_memory_leak
-    assert_no_memory_leak([], '', "#{<<~"begin;"}\n#{<<~'end;'}", "[Bug #19398]", rss: true, limit: 1.5, timeout: 60)
+    assert_no_memory_leak([], '', "#{<<~"begin;"}\n#{<<~'end;'}", "[Bug #19398]", rss: true, limit: 1.5, timeout: 60, samples: 5)
     begin;
-      1_000_000.times do
+      200_000.times do
         ObjectSpace::WeakMap.new
       end
     end;
diff --git a/test/socket/test_addrinfo.rb b/test/socket/test_addrinfo.rb
index 3a53a47674a..6d5a9d92a20 100644
--- a/test/socket/test_addrinfo.rb
+++ b/test/socket/test_addrinfo.rb
@@ -522,12 +522,11 @@ class TestSocketAddrinfo < Test::Unit::TestCase
 
   def test_marshal_memory_leak
     bug11051 = '[ruby-dev:48923] [Bug #11051]'
-    assert_no_memory_leak(%w[-rsocket], <<-PREP, <<-CODE, bug11051, rss: true)
+    assert_no_memory_leak(%w[-rsocket], <<-PREP, <<-CODE, bug11051, rss: true, samples: 2..20)
     d = Marshal.dump(Addrinfo.tcp("127.0.0.1", 80))
-    1000.times {Marshal.load(d)}
     PREP
     GC.start
-    20_000.times {Marshal.load(d)}
+    1_000.times {Marshal.load(d)}
     CODE
   end