It's not clear why you need to chuck that stuff into a hash, but that should not have much effect on execution time compared to the file I/O.

However there are a few foibles in your code that you should consider addressing:

• you should generally use the three parameter open: open FH, '<', "..."
• map { $_ =~ s/[\n\r]//g } @{$sspr_hash{$file_name}}; is probably clearer as $_ =~ s/[\n\r]//g for @{$sspr_hash{$file_name}};
• $_ =~ is redundant in $_ =~ s/[\n\r]//g
• you should always include use strict; use warnings;