Thanks you all, monks.
I tested the regexp vs "eq" thing in grep (using Benchmark qw/timethis/) and "eq" is waaaaaaay faster than the regexp :D
As for the smart match thing, I found out that too, and it seems quite broken. What I find strange is that the various comments go back even to 2010, and I thought it should had been fixed by now (<-- feel free to fix the verbs in the previous sentence, I usually get lost in hypothetical sentences :P ).
I'll benchmark the last solution proposed by brx, just out of curiosity.
Thank you again!