For the regex novices here, would anyone mind explaining what that pattern is meant to match? More specifically, what `.(?:.=.*)` is meant to do?
replies(4):
Slightly more verbosely, it will match [0-or-more bytes of anything] followed by [0-or-more bytes of anything] followed by [an equal sign] followed by [0-or-more bytes of anything]. The expensive part is that it can't decide where the first grouping of [0-or-more bytes of anything] starts and the second grouping begins. It doesn't matter where the division is, of course, but many regex engines use an exponential-time algorithm for that, even though an obvious liner-time algorithm exists (and pre-dates the exponential-time algorithm!).