Navigation frame drops in specific locations of a map

[N3xsX]

After the 3.0 update, I’ve noticed that with around 30 or more NPCs, FPS can drop from 100 to 5 when inside a building - possibly one made of prop_static.
The same number of NPCs causes no issues when I'm either outside or inside buildings made with world brushes.
This wasn't happening before the update, so it seems like a recent change may have affected performance

[DrVrej]

I have never heard of such a thing, do you have a map to replicate it?

[N3xsX]

Yep, here’s an example:
https://steamcommunity.com/sharedfiles/filedetails/?id=2397044635

I know it was working fine before, because I played it just 3 days before the VJ Base update with no issues at all.

Here’s a video showcasing the whole thing:
https://youtu.be/-IVFAYOg6Rc

[DrVrej]

I can confirm that I was able to reproduce this issue. In VJ Base revamp I am simply using Source Engine's chasing system, the one used by the default HL2 NPCs. I don't know what would cause this frame drop, something must be looping like crazy in the engine, I have only seen it happen in this map in specific spots like you mentioned. I don't know how this could be fixed or mitigated through Lua, I am exploring different possible solutions but nothing has been successful at the moment.

[DrVrej]

I have investigated this further, I can't figure out a way around it in Lua, this might be an issue that should be reported to the GMod developers instead.