Extrem input lagg Only in gw2 (with Video) (bug??)

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Over the Last few weeks and months i noticed a bit of Input lagg in GW2 (ONLY in GW2) and i want to ask if someone else has the same problems.I made a video as a show case where i wanted to use my counter attack but it just did nothing, the whole window i could use it and you can see the game registered that i used my skill.this is not always happening but from time to time and as i said its exclusivly in gw2.as you can see my ping is at 40 and nothing else is lagging, just my skills do not activate.