Weird Lag/Screen lock-up issue since patch

[Dreary.6925]

Since the patch I've been getting lockups - where the entire game locks up for about 2 seconds before continuing. This didn't used to happen and it is very jarring, especially when it happens during combat.

 

To replicate -

I've found a place where I can trigger it every time... if you do the Season 2 storyline "No Refuge" in the Silverwastes... after you kill the Centaur... go back down to the bottom where you started the instance, then start running up the stairs - when you get to the top the game freezes for a few seconds... what is this? I use the default graphics setting (GTX1070) and get 80fps but I even turned all graphics settings down to low (best performance setting) and it still happens - Could you please look into it?