Known Bugs 1. Gallery2 doesn't work with PHP5+APC. There is something wrong with the way methods are restored in some edge case I haven't been able to figure out yet. To reproduce install gallery2 and click down to an individual photo. 2. apc_store() probably needs some checks to skip trying to store internal classes. Something along the lines of: if(Z_TYPE_P(val) == IS_OBJECT) { zend_class_entry *ce = Z_OBJCE_P(val); if(ce->type == ZEND_INTERNAL_CLASS) { php_error_docref(NULL TSRMLS_CC, E_WARNING, "Cannot cache internal objects"); RETURN_FALSE; } } in the apc_store() function in php_apc.c but I am wondering if it needs to do more than that. Windows 1. The following configurations (build arguments) have not been implemented yet (*) --enable-apc-mmap Memory mapping support (*) --enable-apc-sem Semaphore locking support (FCNTL replacement) (*) --enable-apc-phreadmutex Thread mutexes, while implemented we should probably rename the internals to thread (*) --enable-apc-pthreadrwlocks Thread mutexes, read/write locking 2. Non-blocking locks is not supported either 3. Update fileinfo to support stat info in a more portable way (see PECL #17903) 4. Check whether the signal handling needs to be enabled, and if it makes sense on Windows