It is what it says.
SpiffyHUD has an issue with Gnetum mod due to the way it handles rendering its HUD elements (TL;DR, it handles it through a mixin meaning it's blah blah blah). Gnetum's author actually made a fix for this, but Spiffy's author denied merging it. I decided to implement it in this addon.
It disables the mixin implementation of the renderer and replaces it with one that relies on appropriate Forge events.
If you don't plan on using Gnetum (or any similar mod) alongside SpiffyHUD, this addon will do nothing.
