Kernel parameter to swapping app memory out of physical RAM. Currently the it defaults to 60, however I have just learned that by setting it to 0 the kernel is given preference to keeping app memory in RAM instead of file caching.

vm.swappiness=0

To be fair it may cause performance issues with certain apps, if so then increase its value to 10 or adjust accordingly.

Further to affect page cache adjust vm.dirty_ratio=10 and vm.dirty_background_ratio=5 for improving database performance