I have had an issue for years that I couldn't pinpoint to a root cause (I'm strongly inclined to think it's a kernel issue). I bought a CM Storm Quickfire TK keyboard with ABNT2 layout.
The issue is: every time I try to type any key that is not a letter or number one, the computer freezes for a full ten seconds before acknowledge the press and showing the character. Tried a bunch of Linux distros through the years and the issue persists. On Windows it works flawlessly.
Just give up trying to debug the problem, but I still have this hole in my heart where the cause of this issue lives.