demerphq++. Thanks for the reply. I did subsequently benchmark Time::Local with _nocheck, and while it was faster than without _nocheck, my home-brew cache was still substantially faster. Interesting that you decided to cache at the hour level, rather than the day. I chose the day level because converting hours to seconds is a relatively trivial calculation, but then again I guess converting days to seconds is too, so maybe caching at the month level would be just as good.

Now I wonder if the different caching level is the reason _nocheck is slower. Perhaps it's due to the additional subroutine call, and not the different caching at all. But again this is all rank speculation... (I'm actively resisting the urge to break out my benchmark.pl and test hour, day, and month-level caching, but I think I need to just be happy with the performance I've got.)

PS: Based on your reply here and to my post about moving averages, I have to wonder if you're not doing something relatively similar? Hopefully my posts have been somewhat helpful to you, but more likely it seems that your posts have been more helpful to me. ;)

Update: Just thought I might clarify a bit:

on further investigation... 10s of thousands more .. calls

Are you sure? I thought the cache worked like this ...

I meant 10s of thousands more calls to timelocal. Your example is essentially how my cache works (though there are a few things I notice that would probably make it a touch quicker than mine). My log has 10s of thousands of entries between each unique day (an entry every 5 seconds, to be precise), so using Perl's math operations instead of a call to timelocal for all those entries is a huge win.