Extreme lag/freeze

Bug Report ID: #486766326

In some situations the game starts to lag extremely and eventually almost freezes. The screen is not entirely frozen. It looks like it switches between two frames back and forth. Sometimes I can try to move away from the laggy area and it will catch itself. Most times it's not possible. But in those cases I can still go back to character selection and log back in. It will not lag until I start moving again. Sometimes I can then move away from the lagging area. Sometimes I can then kill the mobs from afar and fix the lag that way. But not always.

Usually I can see this with Abyss content. But sometimes also with other content.

Another thing I can see during the lag is that the CPU time gets quite high (>500ms). FPS goes down of course to about 1-2 FPS. All other stats seem to stay normal.