It's much quicker to avoid the eval by xoring with a string of 'z's and then counting the nulls: 

my $ans = ( $str ^ ( $SrchStr x length $str ) ) =~ tr[\0][\0];

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In reply to Re:Capturing occurrence counts via tr/// with variable interpolation by BrowserUk
in thread Capturing occurrence counts via tr/// with variable interpolation by KenW

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