backwards regex search is unresponsive

[mc-butler]

Important

This issue was migrated from Trac:

Origin	https://midnight-commander.org/ticket/4564
Reporter	ossi (@ossilator)

i just did a regex search in a fairly large (35MB) log file. forward search was just fine, took a few msec. then i checked the "backwards" box ... big mistake.
the problem isn't so much that it's insanely slow (i can see why it would be, though it's still a bit extreme), but that it froze for several minutes at 100% cpu without any progress indication or way to interrupt it. at some point an appropriate dialog came up, but it's totally unresponsive as well.