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Unreal uses up all cpu while compiling which causes other programs to lag and freeze!

Something has definitely changed since the last time I used it properly over a year ago with i5 4.4Ghz . It’s one thing to take longer to compile stuff but its quite another for the engine to freeze up the whole pc and not allow other programs to run properly when it’s in the background.

I plan to upgrade to ryzen soon but this to me seems like a deeper issue that’s appeared sometime in the last year or so.
Why does material compiling take such processing?

Does unity have this issue? I only briefly used it before but it seemed like stuff just worked when you added new content.
Id like to see some proper performance optimization and if possible offload the processing to the gpu if its material related.

OMG your i5 is no slouch at all, my i5 similarly is struggling, but ya myself upgrading to ryzen5 soon as I can, prob. 5 2600X. If you have what seems to be i5-7640X ,ya its a legitimate concern.

Unity dunno,but ya light building in unity will bottom out as ue4, with insufficient ram.

Depending on how many cores/threads you have, ya a huge concern, and of course ram is huge.

Yeah something really change a number of versions ago and since than ue4 is just really poor when it comes to compile times. Doesn’t look like much will be done about it though so i guess its time to upgrade.

So i got a ryzen 3600 and while compile times improved quite a bit the editor still manages to cause freezing and stuttering at times. Surely it’s unacceptable behaviour for any software to hog 100% cpu to the point of disruption? Come on epic this is sloppy for an professional aaa dev… :confused:

It’s interesting that I have experienced the same problem, and it’s also not utilizing anywhere near 8 GB RAM that is a required minimum. The laptop I use UE 4.24.3 on has 6 GB of DDR3, a 2.4 GHz Intel Core i7 5500U (integrated graphics, but has DX12), and only 3 GB is actually available for things other than the OS and basics. I think there’s an issue with HOW the shaders are compiled, not that there’s thousands compiling (though reducing that per project start / change would become a more reasonably efficient processing). I’ll keep the editor window open and it is ultra slow to compile, say after a major lighting / material change or a restart, but when I minimize the window it somehow goes noticeably faster and finishes a few thousand shaders in several minutes rather than 15-20. And that’s when the setting to de-prioritize on minimize is enabled for the project.

I’m considering Ryzen 3rd Generation too, and at least 32 GB RAM. But if it doesn’t produce better results, how am I going to continue using UE?

You can reduce the amount of cores that are used when compiling. RAM has nothing to do with it on my system at least, it’s far from even half full…

Was just about to hit search on this topic before looking to the top of the page. I recently decided to pickup and re-learn unreal since I have not touched it since 2008, but im having the same issue. Even when trying to launch one of the starter scenes as vanilla as it comes my CPU gets locked up. I run an i7 - 8700K 3.7ghz and 64 gb of ram so I can only imagine its something I need to fix in settings somewhere.

If its taking up this much power to compile a basic script there is no way a full project will be any different. Any assistance in this would be greatly appreciated.

It was found out that something must have changed between versions over a year ago because it never used to behave like this. It was actually perfecly fine and not disrupting everything else because even on old slow cpu’s it was fine compiling etc.

See here: Almost impossible to work with materials, crazy slowdowns after an update. - Rendering - Unreal Engine Forums

Yep, it looks like a change in 4.25. This can even free 32-thread Threadripper, didn’t happen previously. I could play a 3D game while compiling the engine.
Now, I have like a minut freeze while building engine from the scratch or launching a big project with DDC cleaned up.

Ah well doesn’t look like it’s going to improve any time soon but I really hope things get better when UE5 releases next year.