The screenshot above is taken in the "Bandit Hideout" map, and I'm standing where most of the action happens.
How many torches/fires/candles do you see? 2? 3 ?4
How many torches/fires/candles can the engine see? More than 20, and it will render all of their fire effects, no matter if there's a tree, a hill or twenty walls between you and them.
The performance impact from that is pretty big. If the map has water and you have reflections enabled, it will be twice as big.
So, when you're making a map, please adhere to the following guidelines:
1)
use objects that emit particles sparingly. Especially placing dozens of them in an area where people go rarely adds very little to the map, while still decreasing performance for everyone.
2) use torch_night instead of torch, unless you want to place it in a poorly lit area indoors.
Here's another good example of
please-kill-my-FPS: