Converting from disk based to memory based, and vice versa, is a bit more difficult. When that is done, rename .db. FLAT to .db.new. Start up the game. A comparison of disk based and memory based database storage methods.
Faster database saves.
On a memory based setup, it will only reduce memory usage. You should juggle these options until you find a setup that works, and gives you the best performance. There is no 'right' way to set up a MUSH, it always depends on the capabilities of the system you are running on, and how much of those capabilities you can use. It also enables memory tracing, where all allocation information is written to a file called mtrace.out in the game directory. The awk script mtrace.awk is included and analyzes mtrace.out for potential problems.