The following pattern is inefficient:
r'([ \f\t]*)([=:]*)([ \f\t]*)(.*(?<!\\)(?:\\{2})*)(\\)(?!\\)$
https://github.com/pygments/pygments/blob/master/pygments/lexers/configs.py#L141