I am planning to make a topsites list.
But before some time I had a topsite script in PHP and it was very heavy and my hosting provider told to stop this script. Is it better to use perl script?

I don't really know Perl... But knowing PHP I can tell you that unless whatever you downloaded has a really crappy, laggy design you should of been fine.
I can design you one for under $20 with all the features you could possibly want. (And know it won't lag your server down like the last one)
Although it could of called some functions that your host didn't like and that may be why.
PM me if you're interested.

It is about optimization, I'm doing both PHP and Perl. Perl is more powerful and quicker too. However, PHP is easier for coding and it is HTML embeded language.

From my opinion, you can use any language to do this work but you must optimize its performance, especially Memory Usage.