diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb
index 37375c0e3a..ae2bf82bb8 100644
--- a/test/ruby/test_regexp.rb
+++ b/test/ruby/test_regexp.rb
@@ -1765,4 +1765,11 @@ class TestRegexp < Test::Unit::TestCase
     assert_raise(TypeError) {Regexp.linear_time?(nil)}
     assert_raise(TypeError) {Regexp.linear_time?(Regexp.allocate)}
   end
+
+  def test_linear_performance
+    pre = ->(n) {[Regexp.new("a?" * n + "a" * n), "a" * n]}
+    assert_linear_performance(factor: 29, first: 10, max: 1, pre: pre) do |re, s|
+      re =~ s
+    end
+  end
 end
diff --git a/tool/lib/core_assertions.rb b/tool/lib/core_assertions.rb
index 872402727a..12bff170b1 100644
--- a/tool/lib/core_assertions.rb
+++ b/tool/lib/core_assertions.rb
@@ -738,6 +738,29 @@ eom
       end
       alias all_assertions_foreach assert_all_assertions_foreach
 
+      def assert_linear_performance(factor: 10_000, first: factor, max: 2, pre: ->(n) {n})
+        n = first
+        arg = pre.call(n)
+        tmax = (0..factor).map do
+          st = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+          yield arg
+          (Process.clock_gettime(Process::CLOCK_MONOTONIC) - st)
+        end.max
+
+        1.upto(max) do |i|
+          i += 1 if first >= factor
+          n = i * factor
+          t = tmax * factor
+          arg = pre.call(n)
+          message = "[#{i}]: #{n} in #{t}s"
+          Timeout.timeout(t, nil, message) do
+            st = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+            yield arg
+            assert_operator (Process.clock_gettime(Process::CLOCK_MONOTONIC) - st), :<=, t, message
+          end
+        end
+      end
+
       def diff(exp, act)
         require 'pp'
         q = PP.new(+"")