The issue: Regex can consume a lot of time Prefer over PCRE over EREG (much more powerful and faster!) Bad written regex can consume tons of time (backtracking) C implemented functions are always faster than regex The solution: Think twice about each regex Is there really need for a regex or does a PHP function do the trick? Replace all your EREGs with PCREs Try to avoid backtracking as much as possible (U modifier, if necessary) Reading recommendation: Mastering Regular Expressions (http://www.oreilly.com/catalog/regex/)