I’ve been doing some performance tests on WordPress to see how much of a difference the WordPress Super Cache plugin made.

It turns out that the plugin makes a huge difference.

I kept increasing the rate of requests until the Disk IO rate was the same for both tests. With the cache turned off, CPU usage went through the roof to 400% of my allocation while still only serving up pages at five megabits per second. With the cache enabled, CPU usage settled at 20% and the data rate peaked at over 45 Megabit/sec.

I’m very impressed with the results… It seems that with a moderate spec server, you’ll hit your disk and/or network limit before you run out of CPU or RAM.