Unbearable lag when working with any form of dynamic lighting

It only started to manifest a few days ago, but has slowly but surely become unbearable, causing large lag spikes when I attempt to do anything with dynamic lighting enabled. I've seen laggy maps before, I have a friend whose long run campaign causes massive lag on start up and requires semi frequent refreshes to dispel, but this is a whole another level. Is this all to do with the advanced dynamic lighting update? For the record since I know I will be asked I do not have it enabled, though I did try and then disable it once I saw all the lag it caused, but currently it is not enabled on any map in my game. What can I do? I have a lot of prep work to do for my up coming sessions and with my work schedule very little time to do it, and this is making any progress on my part utterly impossible.

What browser are you in? If Chrome, try Incognito Mode. Ctrl-Shift-N. Some extensions, such as Lastpass, can cause nasty lag. If Firefox, try version 57 (revamped CSS engine), or see whether Chrome in Incognito mode works better. Is GPU acceleration on in the browser? If it's not on, there's not much you can do other than using a machine with a better GPU and up-to-date drivers. If it is on, and your machine has an ancient GPU, you can try turning it off and seeing whether software rendering works better. Modern GPUs handle it fine. In the end, performance here is a function of the browser, and what resources the machine the browser runs on can bring to bear. Also, avoid using circles or freehand on the vision layer, they are murder for performance. Rectangles and Polygon/Line only.

Not my thread, but I was having the same issue. I changed my optimization on Chrome and it's working perfectly now. Thanks Thorsten!