Issue #19875 has been updated by nobu (Nobuyoshi Nakada). Status changed from Open to Feedback It seems compiler dependent. My results on x86_64-darwin are: ``` $ ruby -I ./benchmark/benchmark-driver/lib/ benchmark/benchmark-driver/exe/benchmark-driver ~/tmp/string_count_benchmark_driver.yml --executables=/opt/local/bin/ruby{2.7,3.{0,1,2,3}} Calculating ------------------------------------- /opt/local/bin/ruby2.7 /opt/local/bin/ruby3.0 /opt/local/bin/ruby3.1 /opt/local/bin/ruby3.2 /opt/local/bin/ruby3.3 count 171.134 334.699 668.206 666.938 666.382 i/s - 10.000k times in 58.433576s 29.877601s 14.965446s 14.993903s 15.006408s Comparison: count /opt/local/bin/ruby3.1: 668.2 i/s /opt/local/bin/ruby3.2: 666.9 i/s - 1.00x slower /opt/local/bin/ruby3.3: 666.4 i/s - 1.00x slower /opt/local/bin/ruby3.0: 334.7 i/s - 2.00x slower /opt/local/bin/ruby2.7: 171.1 i/s - 3.90x slower ``` ---------------------------------------- Bug #19875: Ruby 2.7 -> 3.1 Performance regression in String#count https://bugs.ruby-lang.org/issues/19875#change-104545 * Author: iz (Illia Zub) * Status: Feedback * Priority: Normal * ruby -v: 3.2.2 * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- `String#count` became slower since Ruby 3.1. Originally found by `@Freaky`: https://github.com/ruby/ruby/pull/4001#issuecomment-1714779781 Compared using the [`benchmark-driver` gem](https://github.com/benchmark-driver/benchmark-driver). ``` $ benchmark-driver tmp/string_count_benchmark_driver.yml --rbenv '3.1.1;3.1.4;2.7.2;3.2.2;3.0.6' Calculating ------------------------------------- 3.1.1 3.1.4 2.7.2 3.2.2 3.0.6 count 465.804 463.741 865.783 462.711 857.395 i/s - 10.000k times in 21.468251s 21.563768s 11.550239s 21.611783s 11.663235s Comparison: count 2.7.2: 865.8 i/s 3.0.6: 857.4 i/s - 1.01x slower 3.1.1: 465.8 i/s - 1.86x slower 3.1.4: 463.7 i/s - 1.87x slower 3.2.2: 462.7 i/s - 1.87x slower ``` Benchmark: ```yml $ cat ./tmp/string_count_benchmark_driver.yml loop_count: 10_000 prelude: | html = "\nruby\n" * 1024 * 1024 benchmark: count: html.count($/) ``` --- *Initially, I noticed the difference between `str.count($/)` and `str.lines.size` when working on the performance improvement: https://serpapi.com/blog/lines-count-failed-deployments/* -- https://bugs.ruby-lang.org/