[Bug 271904] Aparent performance problem with basic and extended regular expressions

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=271904

            Bug ID: 271904
           Summary: Aparent performance problem with basic and extended
                    regular expressions
           Product: Base System
           Version: 13.2-RELEASE
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Many People
          Priority: ---
         Component: bin
          Assignee: bugs@FreeBSD.org
          Reporter: marius@isgate.is

There seems to be a regression in version 13 of FreeBSD affecting
both basic and extended regular expression processing in (for example)
grep(1).

Slow search when using '(|)':

        $ uname -a 
        FreeBSD 13.2-RELEASE releng/13.2-n254617-525ecfdad597 GENERIC

        $ time grep -E '(wordorphrase|differentword)' 150MB-file >/dev/null

        real    0m54.565s
        user    0m54.372s
        sys     0m0.173s

should not take almost a minute to search 150MB file! 
Even worse is 

        $ time grep -i 'differentword' 150MB-file >/dev/null

        real    0m28.060s
        user    0m28.016s
        sys     0m0.038s

almost 30 sek to do a case-insensitive search on a 150MB
text file - compared to:

        $ time grep 'differentword' 150MB-file >/dev/null

        real    0m0.210s
        user    0m0.178s
        sys     0m0.032s

which runs at normal speed.

This all was fine on 12.3 and 12.4  - For example:

        $ uname -a
        FreeBSD 12.3-RELEASE-p11 GENERIC

        $ time grep -E '(wordorphrase|differentword)' 150MB-file >/dev/null

        real    0m0.290s
        user    0m0.219s
        sys     0m0.071s

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