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Giant performance drop after upgrade 4.14 - 4.15.2

Hi there,

after upgrading to 4.15 I have a big problem, to be more specific, a ~50 FPS big problem.

In 4.14 I had average FPS of 50 - 60 in Fullscreen and now I'm struggling between 10 - 15 FPS.

This game is a roleplay game and the world is pretty much focused on nature and I only upgraded because of the issue with the foilage paint tool in 4.14 and now it's basically a headshot, since the editorperformce is really problematic now.

What can I do except reverting the project back to 4.14.3?

Please don't ignorre this topic.

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Product Version: UE 4.15
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asked May 12 '17 at 12:44 PM in Bug Reports

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avatar image Matthew J May 12 '17 at 02:35 PM

Hello LestatDeLioncourt,

I'll be happy to look into this issue for you. We have another report that sounds similar to this that I'm actively working on at the moment which you can find here.

If this is indeed the same issue, you may be able to see an increase in performance by turning on the HBZOcclusion variable. You can do this by typing "r.HBZOcclusion 1" into the console, without the quotes.

In either case, whether this helps or not, can you please run the "ProfileGPU" command, expand the "Scene" section and then send me a screenshot of that entire window? This should give a breakdown of where the frametime is going.

avatar image LestatDeLioncourt May 12 '17 at 03:14 PM

Thanks Matthew for your help, I'm currently at work and I don't have the upper mentioned game on this PC, I'm at home in one hour then I'll try it out and give you an update.

Thanks fot looking into it

avatar image LestatDeLioncourt May 12 '17 at 04:17 PM

Ok, now I could test the HBZOcclusion, but unfortunally it had no effect once I entered r.HBZOcclusion 1 into the console.

I profiled the scene now and attached two screens. I need to say that the only light I have in the scene in the dynamic sun which is controlled by daytime (and a moon at night but it is disabled at day via C++ (at night the sun directional light is disabled)). Was there a big change how UE handles dynamic lighting in 4.15? Grass don't recieve shadows to save performance.Trees & Bushes do, but they already did in previous engine versions. I work on this game since UE 4.0.1, so it has seen many engine upgrades, but this is actually the first time I have a serious issue after an engine upgrade.

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profiler1.jpg (532.7 kB)
profiler2.jpg (542.7 kB)
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1 answer: sort voted first

I typed that incorrectly, it should be HZBOcclusion, not HBZOcclusion. This seems to be a different issue however as you're not getting a large amount of frametime in HZB mipmaps. This may be related to another issue we're looking into which can be found here: UE-44841.

This issue specifically started in the 4.15.2 hotfix, so if you're on 4.15 or 4.15.1 you can ignore the following information, but if you are on 4.15.2, you may be able to fix this by taking the change at this commit on Github. Fortunately, it's only a 1 line change. If you have a source build already, you can make this change and have it immediately. Otherwise, I would suggest getting a Github source build of 4.15.2 so that you can add this change (Note: This change was made directly in 4.16 which I do not recommend developing on at the moment, as it has not yet been released.)

It would be helpful if you could try this to see if it helps. If you have any questions about getting a source build from Github, you should be able to find that information here.

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answered May 12 '17 at 05:31 PM

avatar image LestatDeLioncourt May 12 '17 at 07:11 PM

Thanks Matthew,

actually I used source builds the last 1 1/2 Years, but temporary stopped because the space on my SSD is limited and almost entirely used by Windows, my Game and the sourcebuild (which grew over 45 GB with the Data Cache). I tried to change the path for the Data cache in the BaseEngine.ini but it seemed to be ignorred, so I temporary installed the launcher and launcherbuild of 4.15.2 since I only had 500 MB space left on my SSD. I would love to use a sourcebuild again, but I guess I need a new and bigger SSD first to handle the size. I guess I will went back to 4.14.3 for the moment, buy a new SSD soon and then grab the latest 4,15 branch from GitHub again. Thanks for your help. Can I contact you directly if the issue is still persist once I had the chance to make another sourcebuild?

avatar image Matthew J May 12 '17 at 07:18 PM

You can feel free to post here. I can mark this as resolved in the meantime if you believe it will be a while, and the issue will be reopened whenever you respond. It's best to keep all of the correspondence public in case anyone else experiences this issue and comes across this post.

avatar image LestatDeLioncourt May 12 '17 at 07:53 PM

Sounds fine to me, thanks

avatar image LestatDeLioncourt Jun 18 '17 at 05:14 PM

Hi Matthew,

unfortunally the issue with shadow depth and painted foilage gets worse and worse every update...here is a screenshot from a test I ran today with 4.16.1 and the cost on shadowdepth is even higher than it was in 4.15.3...

To compare: In 4,14,3 the cost on shadowdepth is 9.85ms, in 4.15.3 it was 27.38ms and in 4.16.1 we are at 46ms...

I guess it is probably related to this bug:


But I'm gettin really nervous in the meantime since the cost on shadowdepth increase with every update and makes the game more or less unplayable.

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shadowdepth4.16.jpg (890.8 kB)
avatar image Matthew J Jun 19 '17 at 06:01 PM

It is likely related to that bug report that you linked, so we will likely need to wait until that is fixed.

As for being nervous, there's no reason to be. There is nothing wrong with continuing to develop on 4.14 if it works best for you. Most major projects don't frequently update to the latest engine version, due to unforeseen problems such as this. I would suggest to continue to develop in a build that works for you until this is solved.

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