I solved the problem with @xpander on DISCORD.
I deactivate all the cores of my processor except 2 in the task manager and I went back to 98 FPs constant
I logged in after a couple days away and applied the update and noticed immediately at the character selection screen than my fps was horrible. In game was the same and after asking my guild and in advice channel the following steps were tried: disable all addons revert to 32 bit client at launcher ...
On the "Big Swing" spell, it says "no cooldown" but once the spell is cast, I have 10 sec of cooldown?
Is this a tooltip display bug? Or is this a bug of the spell?