Performance tanks when landing

Bug Reporting Hub Install, Performance & Graphics
1

Please tag your post with #pc and/or #xbox. - PC

Are you on Xbox, Steam or Microsoft Store version?
Steam

Are you using Developer Mode or made changes in it?
No changes made in Developer mode, issue can be reproduced with it on and off.

Brief description of the issue:
When landing, the performance goes from 40-50fps to 12-16fps and the time spent in “Manipulators” goes from 2-3ms to 15-20ms.

Graphics set to 5120x1440, High Preset, no VR

Happens also with empty Community folder (only Flybywire A32NX installed, current Developer Version)

Provide Screenshot(s)/video(s) of the issue encountered:

Detailed steps to reproduce the issue encountered:
Start with Flybywire A32NX at LOWG - 30fps on ground
Fly to EDDM (40-50fps in flight)
Land at EDDM (14-16fps)
If you land at EGLL, you get 12-14 fps
Fly. back to LOWG - 16-18fps when landing

CPU utilization stays constant (40-50% with heavier load on a thread on core 11 (it’s always 11)
Not using any tools like Process lasso or the like
GPU utilization decreases from 60-70% to 20-30% (which explains the drop in fps)

It only happens in DX11.

PC specs and/or peripheral set up if relevant:
i7-8700K @ 4.9GHz, 32GB DDR4 Ram, 2TB SSD for OS and MSFS, dedicated 512GB SSD for packages (Official and Community)
49-inch Dell Ultrasharp Monitor (5120x1440), NVidia RTX 3080, current drivers
Thrustmaster Captain Pack, Logitech rudder pedals

VRAM maxes out at 5-6GB (10GB on card)
System Ram maxes out at 10-11GB (32GB in System)

Build Version # when you first started experiencing this issue:
SU8 - build 1.23.12.0

2

Does it happen with a default aircraft, or just the FBW?

3

It seems to be far less pronounced with Frame rates being much higher in general. In LOWG in the Icon A5, I start off with buttery-smooth 55-60fps which decrease to 40-45fps. So there seems to be more performance overhead with smaller, less detailed aircraft.

Framerate seems to go down massively, when the thread on core 11 is on 100% utilization. So I guess, it’s something running single-threaded which holds back the entire system. This would also explain the GPU utilization going down.

1 Like
4

Your settings are too high/not optimized, when MSFS loads and swaps a whole bunch of extra data nearing the threshold?

5

No, I never had more than 50% ram usage and 60% Vram usage. No swapping, the settings are not the problem.

6

Nothing to do with Vram or Ram, it’s MSFS internal swapping, lower a couple of heavy settings to nothing and test?

7

Optimise your GPU / CPU load at a scenery dense airport. Are you mainthread limiting on landing? I’m guessing so. I have optimised my GPU/CPU loading and instead of aiming for high FPS (which is a bogus metric with this sim) I have FS locked at 30FPS/60Hz and it runs very smooth everywhere at 4k. About 90% of people reporting issue like this are all chasing FPS when there isn’t a CPU/GPU combo on the market today that can run FS at 60FPS solid.
You should optimise your graphics settings balancing your GPU/CPU load for desired performance parked on the ground at say EGLL or KJFK. Monitor your CPU for mainthread limiting if it is then lower your LODs a bit. Seriously consider trying 30FPS at 60Hz refresh rate though as I get very smooth performance all round in FS since doing so. It’s only peoples misconceptions of 30FPS that seems to put people off trying, but FS was designed to run there I think. It’s counterintuitive I know.

8

I have a gaming laptop connected to a 29 inch wide screen and had the same issuses on landing airport lag etc. I tried every thing from low to ultra on off settings and no luck. My screen refresh rate was on 74 hertz which is native setting. I started to play around with refresh rate and set it on 50hertz and now game is running at 25fps and no stutters for me. worth a try. Device name MSI
Processor Intel(R) Core™ i7-8750H CPU @ 2.20GHz 2.20 GHz Nvidia geforce GTX 1050
Installed RAM 16.0 GB (15.8 GB usable) Just changed to 60 herzs and now getting 30fps still smooth.

System type Win 11 Dev 64-bit operating system, x64-based processor

9

There’s an interesting tidbit there the 2 X ratio of FPS to refresh rate. You’re onto something. When refresh rates of monitors are set to be too high for FS, Vsync spends a lot of time trying to sync frames to monitor refresh rate but is challenged due to non whole multples. Stutters common. I’m set to VSync on at 30FPS locked in sim with refresh rate at 60Hz set in NVCP which achieves good smooth v sync and minimal stutters. When you don’t have whole multiples of refresh rates it will affect performance.

2 Likes
10

Be aware

We’d like to remind our users that all the features that have been previewed on Experimental over the past months are now available on the Development version. You can continue to use Experimental if you wish, but you should expect more bugs as we test some further improvements. For day-to-day flying, Development is recommended. It includes holds and all LNAV improvements from the previous Experimental.

Get the Development version through our installer: https://api.flybywiresim.com/installer
Or with a standalone download: https://api.flybywiresim.com/api/v1/download?url=https://flybywiresim-packages.b-cdn.net/vmaster/A32NX-master.zip

11

Since you’re using 3rd party aircraft to test, it might also cause the performance issue.

If I may suggest, perhaps if you can do the same test with the default A320 and empty the Community folder, we can localize the issue. What i mean is, if you still get the performance tanked, then the issue is purely from MSFS/Asobo.

1 Like
12

Hi!
Thanks for your opinion and I agree with everything you wrote. That’s exactly what I’m doing and you’re absolutely right with the assumption that I’m mainthread-limited.

My point is that it’s hard to optimize when the performance at the same airport varies by 4x. When I load up the simulator and sit at the gate, I get 4x the performance than when I land there. And if I optimize for the landing part (which is the worst-case), I end up with less-than-Low Settings. On a 3080. That’s unacceptable. That way, I can stay with xPlane 11 and the Toliss AA321.

13

that’s a great idea! I will try with VSync off (and try to cope with the tearing) and try VSync to 30fps. Let’s see how this works out!

14

Thank you for that answer. I really appreciate that. However, I am using the Development-Version as stated in the original post. I’m not using the Experimental branch.

15

30FPS/refresh rate 60Hz and VSync on should even your perf out. It does it for me, fluidity all round. Note: you still have to balance CPU/GPU loading first.
There appear to be way to many people aiming for high FPS(>30) which is totally unnecessary with this sim. Fluidity all round should be the goal and you don’t get that by targetting higher FPS, all that achieves is 50FPS above clouds and 20FPS on landing/at airport, and endless posts about how bad the sim is running.
I still think the devs should have an optimiser/analyser type tool (hint someone could make a small fortune there!) that recommends settings based on either a desire for high FPS(there will always be those that chase this metric) versus fluidity (what most people want but don’t know how to achieve it with their PC).

16

VSync should be ON but locked at 30FPS RR at 60Hz (set in NVCP for FS). Other setting to try in this regard are here-

17

Thanks for the link, I got your suggestion the first time. Still, I will try it OFF as well.

18

That is your opinion. I think there is a noticable difference between 30 and 60fps and if the simulator is not running smooth without capping it at 30fps, that’s simply bad engine-design. I’m thankful for the workaround but it’s just that and I wish for a better solution from Asobo.

19

FS was designed to run at 30FPS. That people are choosing to try for higher FPS is really down to their choice. But to expect consistant higher frame rates is just a pipe dream of future hardware. About 90% of the performance issues reported on this board are because people think 60FPS consistant is an achievable goal with current market hardware and they expect to get there by ‘magic’ and when they don’t they either try sliding all the graphical sliders to the max or min extremes without realising their individual impact or importance on CPU and GPU loading. Hence my suggestion of an official software based analyser for this purpose. There is no single answer, just a choice between FPS vs smoothness/fluidity, and it differs for every system, but the methodology used to get there is the same.

20

That’s an interesting point you make. I’m not doubting you, but do you have any evidence to back up that the FS was designed to run at 30fps? I’m not aware that this was made public anywhere but I’m always happy to learn.