Uhm, I fail to see what the problem is here. There's nothing wrong with a 100% CPU usage. In fact, 100% CPU usage is what you want. Anything less, and it means you've paid for expensive pieces of metal you aren't using. There's nothing wrong with cache usage either. In a modern OS, every process uses the cache. What you want is a lot of cache hits, and not a lot of cache misses. Unfortunally, Perl isn't very good in this department (due to 1) high memory usage, and 2) lots and lots of pointers). But that's the price you pay for the flexibility you get.