I had a similar problem earlier where I had to speed up the text file parsing part of my application.

Without really going through your code, here are a few tips that may or may not come handy.

I recommend Devel::NYTProf for profiling. It gives you a very nice color-coded, line-by-line report on your code that you can use to figure out exactly where the bottlenecks are.

I found that substr is the fastest way to parse data out of lines that consist of fixed width fields only.

tr/// is faster than s///. (I don't know whether this is applicable here, though.) Anyway, the fewer regexps, the better.

In the inner conditional of your filterLog function, do you really need to test the existence of your $opts{} variables?