Comment # 34 on bug 1112824 from Atri Bhattacharya

(In reply to Michiel Janssens from comment #33)
> There is a possibility that the spectre mitigations have something to do
> with all this, and or hyperthreading/smt.
> 
> 3. boot with kernel parameters:
> spectre_v2=off
> Transition is smooth
> This parameter seems to have the biggest impact of all the tested parameters.
> 

Early days -- minutes, actually -- but this seems to help a lot in my case too
(Intel i7-7*** processors). There are still some animation choppiness on
Application overview, but nothing like before.