I'm not too familiar with the JVM so perhaps I'm missing something here: how would that help? The file is tiny, just a few bytes, so I'd expect the main slowdown to come from system call overhead. With non-mmap file I/O you've got the open/read/close trio, and only one read(2) should be needed, so that's three expensive trips into kernel space. With mmap, you've got open/stat/mmap/munmap/close.

Memory-mapped I/O can be great in some circumstances, but a one-time read of a small file is one of the canonical examples for when it isn't worth the hassle and setup/teardown overhead.