Issue #14418 has been updated by jeremyevans0 (Jeremy Evans). Status changed from Open to Closed Thanks to very impressive work by @makenowjust, this issue has been fixed in Ruby 3.2. ---------------------------------------- Bug #14418: ruby 2.5 slow regexp execution https://bugs.ruby-lang.org/issues/14418#change-104241 * Author: jakub.wozny (Kuba W) * Status: Closed * Priority: Normal * ruby -v: 2.5 * Backport: 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN ---------------------------------------- I have simple regexp that performing very slow. ~~~ ruby "fußball "*20 =~ /^([\S\s]{1000})/i ~~~ It works fast if I remove `/i` flag. I figured out that is also depends on string length or on quantifier value (in this case it is `{1000}`). When you remove `ß` form the string it also works fast. I tested on 2.3.1, 2.4.3 and 2.5.0. I'm not sure it is a bug or it just works that way. -- https://bugs.ruby-lang.org/