If the ads are just text, you only have 100 of them, and you aren't changing them every few seconds, your best option is probably to have them in memory (that is, read them in as the server starts).

But realistically, you probably have some dynamic, or at least, changing content on your website (it's unlikely to have a high volume website nowadays where the only content that isn't static are the ads). So you already have some kind of solution. I'd see whether I could tie the ad system in. Or just outsource the ads to Google.

But has any of this anything to do with Perl? You could go to a Python forum, and ask the same thing.