General Speed and Server Caching

I am advocating a move to PHP for our corporate website as well as our
intranet.  My boss, has raised an issue to which I've found no useful
response.  His question was, can PHP scripts be cached in the server similar
to the way JSPs or ISAPI dlls are handled.  For instance, I have a library
of functions I have already written.  His argument is that the library must
be re-interpretted each time the script is hit.  Is there any way to avoid
that?

Any help is appreciated!

Joshua Groboski
Programmer Analyst / WebMaster
SAVVIS Communications
http://www.savvis.net