Replace
push(@titles, $1) while $source =~ m/<title>(.+)<\/title>/i;
with
push(@titles, $1) while $source =~ m/<title>(.+?)<\/title>/ig;
to 1) avoid matching from the begining of $source every time, and 2) to avoid matching too much.

push(@titles, $source =~ m/<title>(.+?)<\/title>/i);
also works. It might even be faster. However, it uses more memory.

Update: Actually, there should be at most one title, so you want
push(@titles, $1) if $source =~ m/<title>(.+?)<\/title>/i;

In reply to Re: one line regex eating CPU by ikegami
in thread one line regex eating CPU by Anonymous Monk

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