It wouldn't be a problem if this is an application that will run for a long time and that you know it *will* use all this classes soon.

But if this is, for instance, a CGI application, you may want to switch to requires around your code to avoid the loading of classes you won't need in that run. This will reduce not only the memory use, but also the "boot" time.

The question of implementing plugins will not depend on the number of classes (as they might be doing completely different things), but on the number of classes doing the same type of things. Even then, it would depend if you switch on and off some of these classes to make sense (plugin means plug-in *and* plug-out).