[kevincox]

Unless you manually lock the executable in memory it will be evicted from RAM just like any other file on the filesystem. When you start up the usually-idle launcher it will load everything from disk (well load what it needs then the new process will load the rest as it starts up). I doubt the performance difference is significant unless your process does lots of work at startup and you will lose out on ASLR by always forking the same memory layout.

[goldenkey]

On Windows I believe one can call an API like VirtualProtect to prevent swap/eviction from RAM. Should be possible on Linux too?

Yeah, it'd only really be useful if one was running some type of web service that called an executable, and there is no source code available to do any fastCGI or whatnot.