Flight Sim frame rate drops severely at particular altitude range

I have a flight simulator and am experiencing a severe drop in the FPS (from 50-60fps down to single figures - I’ve seen around 1.5fps) when my aircraft goes through a particular altitude range. Below this range everything is fine, above this range everything is fine.

It happens around a height of about 1600 units but there is nothing significant about this height in the game logic - no extra scripts are run, nothing special happens in any of the ones running.

I thought it might be related to the fogging effect as it seems to coincide with the terrain below fogging out but I’ve turned fogging off and it makes no difference.

I’ve noticed spikes in the hard-disk activity during the fps dips so I’m guessing it could be texture related but I’m not sure what to tweak. Something to do with the mipmapping for the terrain?

Any help would be appreciated.

If your camera is angled down, it makes sense that you would get a frame drop when you go up (more terrain exposed). I’ve seen some complex ways around this using terrain splats (mainly from this year’s Unite) but for a quick workaround you could have 2 cameras that view only specific layers. One camera can view the plane, while another the terrain. Just add a simple code to clear the camera or disable it when your altitude gets to high.

I totally know the answer to your FPS problem. Frame rate drops depending on these occasions:

To many objects or you have used terrain

Graphics quality is too high

you did not set the expected frame rate code:

	function Awake () {
		// Make the game run as fast as possible in Windows
		Application.targetFrameRate = 300;

note: you can set the frame rate to any number if you want.

computer is hot and needs cooling ASAP

need bigger RAM

Or, you computer is just slow

These answers are %100 tested and works. This may help you get the speed of the game you want it to go. Or it might just kill you computer(Overwork it).