Latency peaks and freezes

Good day,
Since few weeks now I have some very high latency peaks and unsual screen freezes. I am in NA (Canada, Quebec) and usually my latency is around 100 ms which is not very disabling. But it regularly increases at 1, 2 k, which in raid is totally unplayable....

My connection is not very powerfull but still enough for WoW (~ 50 mbps down, 20 ms, and 30-40 mbps up), so I dont think this is a issue.
I dont have issue with my graphic card (gtx 1050 2g, usually 60-100 fps), I use the latency reducing tool and all the things that reduce latency in the video menu.

I am looking for advices to get a better playing experience.

Thx a lot !