Prototype require class function

Hello PHP.net I'm a big fan of php to code my websites, and uses objects all over. On my website I have in the neighborhood of 80 classes defined in each separate file, which I include in my project in an inc-file using the 'Require ()' function. I have tested the performance and observed that it takes much time to include all the class-files, so I wondered. Is there a way to include class files for the project that do not read files through, but merely creates a prototype of the class. Then, when the class is initialized, the file will be loaded? Sincerely Morten Heebøll