Perl-совместимые регулярные выражения (Perl-compatible regular expressions)
PCRE JUST-IN-TIME COMPILER SUPPORT
Just-in-time compiling is a heavyweight optimization that can
greatly speed up pattern matching. However, it comes at the cost
of extra processing before the match is performed. Therefore, it
is of most benefit when the same pattern is going to be matched
many times. This does not necessarily mean many calls of a
matching function; if the pattern is not anchored, matching
attempts may take place many times at various positions in the
subject, even for a single call. Therefore, if the subject
string is very long, it may still pay to use JIT for one-off
matches.
JIT support applies only to the traditional Perl-compatible
matching function. It does not apply when the DFA matching
function is being used. The code for this support was written by
Zoltan Herczeg.