AMD DXCache?

I noticed the folder Appdata/Local/ AMD/DXCache is about 250MB. Whats the DXCache folder for?

It contains the compiled shader files from the shader cache option in amd radeon settings.

The shader cache stores a collection of parsed and precompiled shaders. ... On-demand shader compiling can cause freezes during the game play and uses extra memory. To reduce this overhead, all required shader combinations for a game are parsed, compiled, and stored in the shader cache.

Shader Cache and Generation - Lumberyard

From my experience it reduces load times in games, which is quite handy.

It is specially useful for those gaming using mechanical Hard Drives.