Coherent has a MASSIVE performance impact on FS24

Aircraft is 1st party C-17.

The C17 has many instances of HTML gauges around the aircraft (a total of 33 individual gauges given the massive size of the aircraft and complexity of the cockpit). Arguably this number could be reduced slightly to optimize the number of gauge instances that are individually rendered, however, problem seems beyond that.

In MSFS24, with Glass Cockpit Rendering Frequency set to HIGH, the CoherentGUI Thread is maxed out (red) and showing approx 40-50ms. Just that single setting drops FPS from ~50s to ~25 on my system
Dropping to medium improves significantly, green with spikes of yellow and around 20ms.
Dropping further to low, consistently green and 15ms.

However, the exact same aircraft, with the exact same gauges in FS20 is having very different results:

All settings maxed out, CoherentGUI is at maximum 11.2 Ms (!!!). That is at maximum refresh rate! Doesnā€™t even get anywhere close to the lowest refresh rate in FS24.

Therefore, and based on these, Iā€™m drawing the conclusion that Coherent is being handled differently in FS24, and thatā€™s having a massive impact in performance across aircraft - despite a general performance improvement all across. Glass Cockpit Refresh Rate is the one setting that consistently has, by far, the largest impact on any aircraft in MSFS using coherent displays.

Keep in mind this is on relatively good hardware, so our followers with lower end PCs are really struggling with it.

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@FlyingRaccoon Pls high prio as it makes the aircraft completely unusable on Xbox.

We have identified that one of our gauges has a particularly high impact on performance (on PC at least), and we are attempting reducing such impact. However, we are unsure if this will do anything to Xbox.

Ultimately, the drastic difference between FS20 and FS24 does seem to indicate that there is an underlying issue beyond our control, and the complex nature of the aircraft just renders any other solution unfeasible.

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I have also experienced a similar behavior with one of our UI mods. Itā€™s now very easy to make the whole sim stutter by mutating the DOM.

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This is really useful to know. In my gauges I create all the html elements ā€œup frontā€ either in the html or the startup of the gauge, but Iā€™m certainly changing the visibility of those elements during flight (e.g. style.display = block | none).

I already have systematic coding that skips updates in JS routines if the previous one was within some chosen timescale, so e.g. my distance-to-go updates only fire per-second, but thatā€™s not going to avoid a stutter if the display update code accidentally includes an inefficient MSFS2024 method.

Any info about what html/js coding has become ā€˜more expensiveā€™ in msfs2024 is valuable, Iā€™m prepared to make coding changes if needed

Bump - our Xbox community is wanting to enjoy the aircraft with decent fps, and we have been able to confirm that the single source of stuttering and performance issues on Xbox is the Coherent displays (basically forced a ā€œinstrument blackoutā€ and FPS increased by over 150%)

Hi everyone,

One of our developers wanted to run a comparison between MSFS 2020 & 2024 on this aircraft but - correct me if I am wrong - it seems exclusively available in 2024 Premium Deluxe & Marketplace.

If you have a 2020 version that we can use for comparison purposes, would it be possible to send it to use through PrivateContent? Alternatively, are there aircraft available in both sims that exhibit the same behavior?

Best regards,

Eric / Asobo

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Correctly, only Premium Deluxe. Will send you an FS20 package on PrivateContent - its broken in some areas but the avionics are the same as FS24.

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Moreover Coherent GT completely hangs a slower PC like mine Win10 i5-7600K during loading procedure at around 25%

Actually I found showing the console (that reports a Coherent GT error at that point) makes the sim jumping over it proceeding to complete the loading (with no console shown the loading procedure just stucks there forever)

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Iā€™ve seen this on my end as well (high-end pc)

@EPellissier any updates?

You can simply use the default sim panels as a benchmark. The ones in 2024 induce a noticeable stutter compared to the 2020 versions.

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Nice stuff of this trick is Iā€™m now able to load the MSFS2024 faster than MSFS2020 on my old PC

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Friendly bump @EPellissier - any news?

We are looking into this - we managed to reproduce the issue and we understand why it occurs. A candidate fix is being implemented.

Best regards,

Eric / Asobo

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Will it also solve the loading issue ?

I cannot look at your screenshot - for some reason its size seems to be very small. I am not sure the issue you reported has anything to do with the initial question - you should probably start a new topic with a bigger screenshot. :wink:

Best regards,

Eric / Asobo

Actually I already did it (and the screen looks better there) :wink:

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I meant creating a new topic on DevSupport, not in the official forums. :wink:
Do you still get this behavior now that carry-over has been largely deactivated?

I could be wrong but I doubt the issue is related to CoherentGT itself - if it cannot find a file thereā€™s no reason why it should prevent the loading from completing. Unless some carried-over item has tried to override a core file of the UI and has completely destroyed the sim UI.

Best regards,

Eric / Asobo

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@EPellissier Unfortunately the issue is still there

When the loading screen is stuck at 25% if I open the console then the following screen is always shown and after few second the procedure restars

If I instead leave the console closed then the loading screen always shows 25% and there is no progress at all after minutes

If I open the console window before reaching the 25% the loading just stops at 25% for few seconds (with the usual error shown) than it proceeds forward

What is reall surprising me is that opening (and keeping it open) the console window actually makes the loading to proceed normally (apart some lables like ā€œVFS Activating packagesā€ that are shown instead of the usual ones)

The plane is not 1st party. Itā€™s Miltech.

Any updates? Any chance a fix may be pushed on the 9th?