LINUX: Solving slow GTK3 apps issue with kernels >=4.6

Several things which can be done:
- You can downgrade to 4.5, which works fine,
- You can downgrade to -lts kernels, which also works just fine.

But the "best" solution appears to just be using a composite manager (I used xcompmgr but I guess you can use whatever you
like), and everything will just work perfectly.