UE4 stutters/hitches in 4.3 update

Since updating to UE 4.3 I notice that pretty soon after the editor is up, it starts stuttering. Even if I’m not playing my game and I just have a new empty project. Every few seconds it’ll pause for about a second or two then continue on. It makes it nearly impossible to work with. If I shut it down and restart it’s fine for a few minutes and then gets messed up again. My other programs running aren’t experiencing this and I don’t see any CPU spikes in task manager. With 4.2 it ran super smooth. Machine specs:

Win 7 64 bit
16GB RAM
AMD FX-8350 CPU (4ghz, 8 cores)
AMD Radeon HD 7970
both hard drives are SSD.

Hi Architekt,

Can you post your dxdiag so we can see your driver information? Also, does this hitch occur when you are doing something specific (editing bsp’s, making materials, etc) or does it occur with various activities?

Hi Architekt,

In the console command window can you type in “stat fps”. When one of these hitches happens does the framerate drop? If so please let me know the normal fps and what it drops to as well as about how long it takes for these hitches to start occurring. Thank you!

It occurs when I’m just sitting there not doing anything, or if I am doing stuff. If I hit play, it’ll stutter while I sit there. If I’m not playing and just idling, it’ll stutter too. It doesn’t look to be specific to any action. I’ve had it happen editing blueprints which used to work perfectly fine. link text

So this is kind of interesting. I did an uninstall and a fresh reinstall to fix a bug I had with not being able to associate my project files with the UE4 launcher (which fixed the issue). Now when I run my game in the editor, if I have input focus on it I don’t get any stuttering. I can however 100% repro the stuttering if I shift-f1 and mouse over various UI elements. For example, if I constantly mouse over items in the Scene Outliner or items in the content browser (the type of element doesn’t matter), then about every 5 seconds I get a full halt of everything in the UE4 editor for about a second. My game FPS goes from 120 to 0. The timing seems very consistent.

It’s not doing it when I mouse over entries in the Modes tab. It is doing it when I mouse over the toolbar (with the save/compile/etc buttons on it). If I just have a blueprint editor window up of my character, without moving the mouse at all and just sitting there, it’ll stutter. The tab doesn’t matter.

And of course right as I post that, it’s not repro’ing anymore. I just did all the steps I mentioned and it’s all smooth. This is weird.

Edit: Alright it’s back. Seems kind of inconsistent.

About how long did it take for the hitching to occur this last time? Also what were you doing just before it occurred?

Well this time it was instant. I just started up UE and made a new blank project, did “stat fps” and waved my mouse over the initially populated actor list in the scene outliner and it just started happening. Sometimes it doesn’t start until a few minutes in. Each time it’s inconsistent what I was doing beforehand. At first I thought maybe my system had an issue and the whole OS was halting. But I did some tests where I’d play a video or have something running beside UE that had an animation (like a flash video in a browser). I’d do the mouse over thing in UE to trigger the stutter, and UE would halt but nothing else on my system would. Everything else kept playing smoothly.

Have you tried running the engine in 4.2 after the 4.3 update to see if it still runs smoothly? If not, please try running it in 4.2 again to see if the hitching occurs.

Hi Architekt,

We have not heard from you in quite some time. I am marking this thread as answered for tracking purposes. If you are still experiencing this issue, please comment with the requested information. Thank you!