PHP Extensions: are they inefficient when using the extension keyword in php.ini?

After reading the PHP online documentation for "Chapter 25. Extension Possibilities" I am confused. I have a set of questions below: 1) compiled versus extension versus dl function: It appears to say that if an extension is NOT compiled in and IS used as a shared module that the module is loaded at each request and unloaded after each page finishes. And that this is slooow. Even if we use the "extension" keyword in the php.ini file it is still slooow (i.e., the same effect as using the dl() function). a) Can somone who knows clarify/assert this? b) Because we use pgsql as an extension (set in php.ini) and we use it very heavily on every page. One would think that there would be significant performance advantages to gain by "compiling in" this module. Would this be the case? 2) I was also under the impression that all of the built-in PHP modules (which, to me is the entire set of modules in the documentation pages at the PHP web site) are compiled in and fast and that php doesnt need to load them in for EVERY request. I am dissappointed that PHP needs to load and unload each shared module for EVERY request. 3) The PHP documentation laso states that this loading and unloading of the shared module is "very slow". Can anyone qualify this - what do they really mean? We are using it with Apache. Mike Papper