I was just curious as to how much memory use per page load is too much? I know this may vary depending on the resources of the server, so for general purposes let's just compare this to a virtual dedi. setup with 512 MB of memory.

In an app I am writing, without caching the page load is generally around 2 - 3 MB per page load (KohanaPHP framework). Is this too high or will it cause performance issues? I know this is per page load, and in my case I probably won't see several hundred thousand users per day ( prob. more around 2 thousand a day ).

I also understand some caching methods will use more memory but probably less CPU. Anyone have any insight into memory/cpu usage in your projects?