Was travelling through Howling Fjord to turn in dungeon quests, as I was going across the bridge to get to Utgarde Keep the game client went EXTREMELY slow. I was unable to move since something was trying to load/parse and it just would not comply. The game would load a single frame once every few minutes. I've highlighted the area on the map below:
In an attempt to get out of the location so I could continue playing, I disabled all addons, turned graphics all the way down and lowered resolution and it made absolutely no difference. The only way I got out was by spamming my hearthstone which was thankfully on one of my bars.
I get a similar issue when I'm in Dalaran althoguh it only occurs for 1-5 seconds while the game client is trying to load the multitude of players. Not even close to what was taking place at that bridge.
I have a Ryzen 7 5800x and 3070ti so my PC is not the issue, internet is fine, everything runs at a high standard otherwise.