$_ = 'fo ba' x 1000 . 'foo bar'; Benchmark: timing 10000 iterations of Loop, RE... Loop: 1 wallclock secs ( 0.71 usr + 0.00 sys = 0.71 CPU) @ 14064.70/s (n=10000) RE: 12 wallclock secs (11.10 usr + 0.00 sys = 11.10 CPU) @ 901.23/s (n=10000) Rate RE Loop RE 901/s -- -94% Loop 14065/s 1461% --