With the change in #7955, if the regex did not match, it ended up retrying the
lookahead at every position of the string (expected), but then *also* repeated
that process for every position in the string. Thus, a non-matching pattern
ended up in O(n^2) performance (with n = length of URL).
Instead, anchor the pattern at the beginning of the string. This doesn't change
behaviour as we use .* at the beginning of every lookahead anyways, but it means
we end up with O(n) instead of O(n^2) performance.
Co-authored-by: toofar <toofar@spalge.com>
ee9aecda46