Custom/Certian NPC's lag after spawning only a few on different maps

I’ve tried Googling this but haven’t found anything relatable. So I’m using an addon from workshop called NextBot Zombies, and after I spawn more than 10 - 15 on sandbox, my FPS drop to about 5. However, when I do it with any of the Hl2 bots I get no lag whatsoever and I can spawn dozens just fine.

At first I figured it might just be the addon, but I tried it on several maps and something interesting happened - I had to generate the .nav via console for the two custom maps I tried it on to make the NPC paths (rp_silent hill and another zombie map I can’t remember the exact name of, but it was the town from one of the L4D campaigns) and after I did that, both maps gave me the problem. But when I tried it on gm_construct (Which btw, for whatever reason rebuilds the Nodegraphs every time I start the map) I was able to actually spawn them just fine, about 3 to 4 times as much before I got any kind of really bad lag.

I have not tried any other custom NPC’s because atm I don’t feel like downloading anything else to test before seeing if there’s a quick fix to this problem. I believe it had something to do with gm_construct rebuilding the graphs every time it loads although I cannot prove this; and if there is a command to rebuild Nodes in the console for a map I do not know it and can’t find it online. (Probably because I’m retarded.)

Also, I didn’t ask on the workshop page because I have no idea how long it will take to get an answer from the creator and yet again, I wanted to see if anyone else had any answers here first.

Thanks in advance.

Bump. I already asked the owner and am waiting for his response, but I want to see if anyone knows anything here.