If you're anyway fork/exec'ing a program you'd run before (which you have, if your're in an environment where this would matter), the binary is anyway cached in

If you're anyway fork/exec'ing a program you'd run before (which you have, if your're in an environment where this would matter), the binary is anyway cached in memory by the filesystem cache. But you don't have the processing overhead of doing the dynamic linking and possible relocation, nor do you pay the overhead of calling functions in a shared library. If the library is relocated, you don't even save memory. For overly large programs, statically linking in e.g. an X11 enviroment, it might matter.