“ For instance, when compiling /Sun|Mon/ the automaton representation lets us recognize that both alternatives have an ‘n’ as their third character. We can quickly scan the input until we find an ‘n’ and then start to match the regexp two characters earlier. Irregexp looks up to four characters ahead and matches up to four characters at a time.
Chromium Blog: Irregexp, Google Chrome’s New Regexp Implementation (via ku)
