This is a plugin that allows you to adjust some NIC parameters, disk caching, and other tweaks.  Some users have found that these tweaks will improve media streaming and gaming performance of VMs.  Feel free to experiment, but I don't recommend just cranking everything up to the maximum values.  Doing that may be counterproductive.  You will have an impact on RAM used, and may create a situation where Linux kills some processes to recover memory causing all sorts of problems with Unraid.