Ok, so for my websites i'm balancing RAM usage and speed.  The current setting on this page is using Xcache (APC isn't an option ... yet) for opcode caching and without using FastCGI.

I am trying to understand the difference between the two and i'm not quite getting it.  What is the difference between the two of them?  Xcache sticks compiled php code somewhere in memory (but not within the processes, therefore after php5.cgi executes to build a page, it's closed out), FastCGI keeps the process resident.

My guess is this

Code -> compiled code -> executable code in memory -> execute

Xcache caches the compiled code and that's pulled into memory as needed

FastCGI holds the executable code in memory to execute as needed

Is this correct?  FastCGI is forcing a rather high and persistant RAM usage since everything holds in memory (between my sites I hold at 300MB, without FastCGI it's at 100MB).  Given that it's 10 cents a MB, that's about 20 additional bucks a month.  Then again with the current Xcache implementation, the speed of this site seems acceptable (at least to me, let me know if it isn't).

Thanks for correcting anything that's wrong!

V