Kerbal Space Program

When flying a fast plane or rocket, during rendering of the atmospheric effects on the hull, and probably also re-entry heating-effects (not tested though), the CPU load increases when the atmospheric effects are visible on the plane, and framerate drops (in my case) from 60 to 36, which is quite a excessive drop. When the atmospheric effects are gone, the framerate returns to 60.

• In the following video I demonstrate the problem: https://youtu.be/mE1ro_bKqmA

(NOTE: Not sure how to categorize this problem.. I've put it under 'Physics', but I am not sure it is due to physics or something else.)

Steps to Replicate:

I'd say: see the video above! But here's a description:

1. Do a clean install of KSP (I used the Steam version)
2. Make sure some way of showing the framerate is enabled (I used Steam's framerate overlay)
3. It can be useful to use Process Explorer or any other tool to keep track of KSP's GPU and CPU loads.
4. Start the game (In windowed mode it's easier to keep track of GPU loads and to do quick context switches)
5. Fly a plane or rocket faster than approximately 250 m/s (I used the Osprey plane) to trigger the atmospheric effects and notice the increased CPU load and drop in framerate!
6. Everything returns to normal when the atmospheric effects disappear.

The process is persistent and can be easily repeated.

Expected:

No drop in framerate during visible atmospheric effects on hull.

Result/Observed:

Drop in framerate during visible atmospheric effects on hull.

Fixes/Workarounds:

None known.

Notes:

The video above was recorded directly after recording a video for another issue.

Hence, only the last part of the log files are probably relevant, as the (bigger) first part is related this other video I shot (for a different framerate issue, https://youtu.be/PCJWhRBzCu0)

Version:

both 64bit and 32bit:

build id = 01230
2016.04.19 at 19:58:54 CEST
Branch: master