Falls fps (Garry's Mod)

Help to understand why.
Installed a lot of mods, but when Spanish 25-30+ NPC fps drops to ~30
when the map pure-stable 60fps(SteamFPS)
On the map(can't remember the name) sinking ship fps 55~ as soon as I put different objects falls sharply. When you are in the stage of drowning, the fps drops to 10 and then to 3, with conditions if Spawner lot of NPCs or put a lot of objects.
PC
GTX-1080
Percent PTS old AMD 4100 3.20 4ядр. But soon to change to i7 I
RAM-8GB
Wind - 10
But I have a feeling that the blame for the old cent.