https://issues.dlang.org/show_bug.cgi?id=18114
--- Comment #4 from Jon Degenhardt <jrdemail2000-dl...@yahoo.com> --- The two programs attached can be used to compare regex match performance. Compile find_regex.d with both DMD 2.077.1 and DMD 2.078.0-beta1. eg. $ dmd2.078.0-beta1 -release -O -inline -boundscheck=off find_regex.d -of=find_regex.dmd2.078.0-beta1 $dmd2.077.1 -release -O -inline -boundscheck=off find_regex.d -of=find_regex.dmd2.077.1 Build gen_strings also. Then run like: $ ./gen_strings 10000000 | ./find_regex.dmd2.077.1 'abc' 106438 matches; 3780.769 milliseconds $ ./gen_strings 10000000 | ./find_regex.dmd2.078.0-beta1 'abc' 106438 matches; 6315.638 milliseconds Times on my MacBook Pro for a couple of regexes (replace 'abc' in the commands above): | Regex | 2.077.1 | 2.078.0-beta1 | | 'abc' | 3780.769 ms | 6315.638 ms | | '(aa)+(cc)+g' | 5306.169 ms | 7753.435 ms | | '(aa|ax).+[gxb][cyw]' | 9888.508 ms | 12324.285 ms | --