how can i cache php scripts enterpretet

I have developed a web portal for big compamies with a lot of traffic on their pages. main functions, like member authentication etc. are called on every page request. it would make sence to have them ready enterpretet to skip enterpretation on each request. i know that there are tools arround like Zent Cache. however they require an recompilation/binding on the server. but this is on such big corporate servers almost impossible. Does anybody know a solution for that ?