Engine starts running very slow when lightning needs to be built?


First of all, sorry if this is in the wrong section of the forum! Was not sure which section to post this in.

So I am currently working on a rather large environment and have recently stumbled upon an issue. When lightning is built everything runs super smooth “90 - 120+ fps” but as soon as I place a new object in the scene and the “Lightning needs to be rebuilt” message pops up the fps drops drastically down to like 10-25 fps. I then build the lightning again which takes a while due to the large environment with many assets but should the change really be this drastic? It has made working with this environment quiet a pain due to the sudden low performance the moment I start expanding it with new assets. Is there a work around for this? Could not find much about the issue so figured i’d make a forum post about it!

Computer Specs:
Nvidia 1070 8gb VRAM
i7 6700k 4.01ghz (Skylake)
16gb DDR5 ram
Windows 10

You can limit the priority of the process of lightmass or restrict it to only run on certain cores.

what lights do you use/what’s the configuration like? If you’re using something very unique it may be challenging the engines shading and lighting.

Before the lighting is built it uses dynamic lighting to show a preview of the shadows which has a bigger performance impact.