Performance Tips?

Hi guys, i’m developing a game with BGE and i have a couple of questions about how some stuff works

I want to know in which way Texture Maps, materials, Mesh (polycount), LODS and lights affects the game performance

  • Polycount - I found out that the game slows down only when i have a lot (a LOT) of polygons rendered at the same time on the game. But what about i maintain the game rendering only reduced number of polys (like 100-200k) when my entire scene have something between 10kk, 20kk? In which way the entire scene polys will affect the performance?
  • Material - Having a lot of materials influences very bad on the performance? Or texture maps/images used on the material influences more?
  • Textures (quantity and size) - I noticed that the textures can destroy a game performance if not used with caution. For what i’ve seen, the size of texture image affects directly on the rendering performance. My questions are: does only the size of the texture influences on the performance or the quantity too? For instance, if a have one 4096x texture, it will be more heavy for performance than having four 1024x texture? Or eight 512x textures
  • Images - Having image files that is not used on the game affects performance? I use a lot images on viewport to use as reference or paint brushes
  • Textures Normal/Specular maps - I know that the quality will not be the same, but using a single Diffuse texture with normal and another options turned on is more optimal than having textures for each function?
  • Textures Alpha maps - I like to use alpha maps to cover high detailed areas on a scene, or making some effects like a mossy wall, ray lights or fog, but i don’t have any clue of the influence of alpha maps on performance.
  • LOD - While LOD helps to maintain the rendered polys on the scene to a nice count, they can overload memory ram? So is better having LOD only on high poly meshes?
  • Mist - I’m doing a horror game on a closed environment, so using mist give a really nice effect, but i don’t know how much it affects the game performance
  • Lights - As a terror game, light and shadows plays main hole here. I kinda know how to deal with the shadows, but i noticed that more the lamps in the game, more the fps will be dropped. I want to know if the different lamps affects the performance on the same way (spot affects performance in the same way spot does?) and what variables of lamps kills more the performance (size, energy…)
  • Nodes, Ramps… how they affect the overall performance? Is worth using them for minor tweaks?

Sorry about the long text. I’ve already seen some tips from Monster and ThaTimst3r (thanks guys!). I already have made scene for the game and it in performance terms is very good, but i want to balance the performance and quality to maximum as possible, so i want to make sure exaclty how theses stuffs works. Sorry for my bad english and thanks guys! :smiley: