It doesn't always work as expected. Some time ago I worked on a slot machine that would have an occasional stutter in the reel spin. Eventually the decision was made that memory was too constrained so more RAM was added to the system.
This made the problem worse, not better. It turns out that the stutter was caused by the JVM garbage collection. With more memory there could be more garbage that took longer to collect.
Memory is cheap, good programming is better. 