[Bacardi]

It's normal, game engine calculate "collide" and physics.
By the way, why you use noblock plugin in csgo? It have own cvar for it.

...more players in same "sector", more cpu and network bandwidth in use.
CSGO also is not light game anymore, because all those different player/weapon models and skins etc. etc. to share.

Also if map is created and optimized well using map tools textures, server get less burden.
Main key is, hide most players from each other.