Long-term CPU hit after moving through grass

We have two glider models which suffer a serious FPS impact (CPU Main Thread)
after the models have moved through the high grass on airfields on landing or
takeoff. An FPS halving would be typical. The planes (AS33, LS4 freeware on
flightsim.to) are gliders so they’re close to the
ground. There are two peculiarities and any help would be appreciated: * It
seems like an obvious culprit should be the mesh using the Environment
Occluder material but even if I remove the material “extensions” entry in the
GLTF file the CPU hit still occurs. FWIW I also removed the stock Asobo pilot
model in case it was that. * After the CPU hit occurs, that FPS hit continues
for the rest of the flight, i.e. the graphics engine doesn’t recover once
you’re airborne. The GLTF entry looks like this, in case that provides clues.

            "name": "Enviro_excluder",
            "pbrMetallicRoughness": {
                "baseColorFactor": [
            "extensions": {
                "ASOBO_material_environment_occluder": {}

Hello @B21 I was able to reproduce this framerate loss. We will have a look.
Regards, Sylvain

Hello @B21 Your framerate loss seems to come from legacy effects evaluation.
The [EFFECTS] section of your aircraft.cfg seems to define all legacy effects.
Except for light effects, those are no longer rendered but an issue on our
side causes them to still have a cost in performance. The problem disappears
if you clean this section and remove all non light related effects. We will
update our documentation about this. Regards, Sylvain

Wow - that analysis is incredible. Thank you so much for your help!

Confirmed - I’ve removed that [EFFECTS] section from the aircraft.cfg and my
FPS hit is now completely absent. This incredible support from @FlyingRaccoon
has saved me countless hours of further diagnosis on the plane, swapping out
the model, removing html instruments, etc to try and track down my issue.
Really, really great support that I’d never have expected from a team with
such a large franchise and so many users and developers to support.

I am glad we could help :wink: