This thread discusses the Content article: Benchmarking PageCache

Comparing with the Joomla 1.5.1 benchmarks, it looks like Joomla 1.0.14 with PageCache is pumping out more than twice as many page requests per second than the Joomla 1.5.1 best case scenario results. Yet another excuse not to migrate yet?

Indeed looks like 1.5.1 will only start to be 'faster' once we have all the plugins streamlined for it.

One question though looking at the graphs here and the Opcode caches, they both show a 50% increase yet when the two are coupled file v the best benchmarking Opcode (eAccelerator)the difference is minimal most likely only by a % or two.

So my question is what gives? shouldnt the caching be more effective with one of these enabled by a greater margin?

I can't explain that. I thought memory access would be more significant that that too, but the numbers show otherwise.