[Bend3R]

Already know this is HL1 section. I referred to which game(s). Counter-Strike, ok then.
Set maxplayers to 1 with no mods installed on the server. Now you have this "super stabile low usage"!
About bandwidth and FPS, I can not give an good answer for it.
Good luck with that if you have any high traffic plugins installed.

I prefer Windows for hosting since I'm a Windows user.