Instead, rely on the OS page cache to keep the contents of frequently accessed files in memory.
This shouldn't really be a problem since libjeffpc hasn't had a proper file caching implementation for FreeBSD and there haven't been any performance issues. A post still takes single digit number of milliseconds to render.
This may be a really bad idea if fmt4 ends up cpu-heavy to parse. Parsing each post every time could be prohibitively expensive.