You'd have to have enough RAM to hold the whole model in memory or performance will be awful, mmap is just a way to get faster startup (if the mmap'd file looks

You'd have to have enough RAM to hold the whole model in memory or performance will be awful, mmap is just a way to get faster startup (if the mmap'd file looks exactly like the in-memory representation) and easier sharing (the mmap region can be shared read-only memory that multiple processes use).