Firstly, none of your cases are the same. You could use:

if(  $type =~ /^CR\Z/i  )
# or
if(  $type =~ /^CR$/i  )
# if you want to allow for ignoring trailing newlines
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and you'd have to use: if(  $type eq 'cr'  ||  $type eq 'CR'  ||  $type eq 'Cr'  ||  $type eq 'cR'  )

I'd argue that the speed difference is of extremely little importance in this case.

Use whichever makes the most readable code. So that eliminates the second one in my book. I like the first one.

        - tye (but my friends call me "Tye")