Significant FPS drop (~15 FPS) with TDS GTN 750 in AirfoilLabs King Air 350 (XP12)

[sViterbi]

Hi all,

I’m running X-Plane 12 on Windows and recently purchased the AirfoilLabs King Air 350 and the TDS GTN 750, where I notice a consistent and quite significant performance hit.

Issue:
When I turn on the TDS GTN 750, I experience an FPS drop of around 15 FPS (raw, not frame-gen). The drop is immediate and consistent.

Details:

Aircraft: Airfoillabs King Air 350

Add-on: TDS GTN 750

OS: Windows

Simulator: X-Plane 12

FPS impact: ~ -15 FPS when GTN is in use

Observations:

FPS is stable and acceptable without the GTN 750

As soon as the GTN is turned on / displayed, FPS drops noticeably

The performance hit persists throughout the flight

No FPS drop observed with default avionics in the same aircraft

Question:
Is this expected behavior due to how the TDS GTN 750 is rendered (e.g., external process, CPU/GPU load), or could something be misconfigured on my side?

Any known tweaks or settings to reduce the performance impact?

Thanks in advance!

[adminOwner2]

Hello,

This is a bit unusual behavior, as the TDS GTNXi XPlane runs utilizing external processes, the performance should not be impacted at all, due to this technology there should be minimal to no performance drop when utilizing the TDS GTNXi XPlane.

Can you please test the same scenario with the freeware KingAir C90B:
forums.x-plane.org/files/file/92114-king-air-c90b-evo-gnsgtn-blackhawk-xp12

And let us know of the performance, as the C90B utilizes a different (aircraft side) drawing method than the AirfoilLabs KingAir 350.

Please state your full system specs.

In addition, as a test, you can try lowering the X-Plane 12 graphics settings a bit so there will be a little room available for each PC Trainer process.

[sViterbi]

Hi, thanks for the prompt reply and the support!

The test with the freeware KingAir C90B, was successful, meaning that I have no FPS hit at all, when turning on the avionics.

My system specs are below, but generally, my system has the space for processing the GTNs without lowering the XP12 graphics. Keep in mind that I am in the range of 80s FPS before turning on the avionics. After turning the avionics on, a) in the AirfoilLabs KA350, it drops to 62-65 FPS, and b) in the C90B, there is zero impact, as said above.

System specs:
Custom Double Loop Water-cooled PC
MB: Asus ROG Crosshair X870E Hero
CPU: AMD 9950X3D
GPU: AORUS GeForce RTX™ 5090 XTREME WATERFORCE WB 32G
RAM: Trident Z5 Neo RGBDDR5-6000 CL28-36-36-96 1.35V96GB (2x48GB)AMD EXPO
Storage: Samsung SSD 9100 PRO NVMe M.2 4TB PCIe Gen. 5 x4

[adminOwner2]

Hello,

Thank you for the information, as an additional test, can you please also test a dual GTNXi config (750Xi + 650Xi) in the default C172 with the TDS GTNXi integration.
https://forums.x-plane.org/files/file/94...ompatible/

As the test with the C90B was successful, we think, but we are not sure yet, that the new drawing technique utilized (custom avionics devices), seem to have a great performance improvement. This change mu be performed on the aircraft side, from the TDS side we have done our part and we have implemented all these X-Plane 12.1+ techniques.
An important information: custom avionics devices are the official and only method of drawing LCD touchscreens, the previous method, using the panel.png, while widely used, does not seem to be effective. The change is very easy and must be performed by AirFoilLabs. From the TDS side we offer all our advice and expertise to any developer wanting to integrated this method and have a proper, correct and official integration, thus adding extra benefit to the users.

[sViterbi]

Hi,

The new test is also successful, meaning the C172 with 750Xi + 650Xi, has no impact on the FPS.

Sorry, rushed into an answer using the wrong plane. When I have the linked a/c (C172 you pointed out), XP12 crashes and can't launch on the airport.

But my question is that, if this is indeed due to the new drawing technique, wouldn’t this be a problem already reported by many users? I mean the combo of KA350 with the GTN750 integration is a very popular one, right? Despite this, I cannot find a single reference of this problem online.

On the same tone, wouldn’t you also be already aware of the root cause, from other customers, before my case?
I will of course convey the message to AirfoilLabs, see their comments, and will come back here to update this thread.

[adminOwner2]

Hello,

It seems that you have the only report of the slow performance using panel.png method and two GTN 750Xi units. The AirfoilLabs KingAir must be a bit more FPS intensive than other aircraft, so something could be aircraft related as well.

We pride ourselves with excellent TDS GTNXi XPlane performance, so from the TDS end we will always do our best.

[adminOwner2]

In regards to the C172 crash, can you please update the TDS GTNXi XPlane to the latest released, V1.0.1.4 and try again?

[sViterbi]

Thanks, will also try the V1.0.1.4 for the crash. I have also raised a ticket with AirfoilLabs, I will keep you posted.

Thanks for all your help so far!