32 gigs of RAM. The file on disk is only 34M. My perl is 5.36.3 on cygwin.

I just ran it on another system (Linux) on the same file and got: 
0.457707 read lines from disk and do RE.
0.675398 read lines from in-memory file and do RE.

[download]
So it seems to be specific to my system. It doesn't seem to be memory as it only uses around 34M RAM when running on that file and my memory is nowhere near exhausted.

In reply to Re^2: RE on lines read from in-memory scalar is very slow by Danny
in thread RE on lines read from in-memory scalar is very slow by Danny

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