LarsThiessenSep 27, 2025
It's understandable that Unreal needs to touch a lot of files when starting the editor. But what if I told you that more than 5500 of those files are not needed for the editor to start at all and are just adding multiple seconds to the editor launch time?
Let's fix this!
#UE5 #gamedev
https://larstofus.com/2025/09/27/speeding-up-the-unreal-editor-launch-by-not-opening-5500-files/
Speeding up the Unreal Editor launch by … not opening 5500 files?

In my last article I wrote about some tooltip optimization to reduce the start time of the Unreal Editor by 2-5 seconds. Turns out people do really care about their editor start time. So much that …

Larst Of Us
Show threadAras PranckevičiusSep 28, 2025

@LarsThiessen Excellent work! (also, I see @superluminal screenshots, I like :))

I suspect finding and fixing these types of small slowdowns can be a fulltime job at this scale. My last several years at Unity were similar, but it is an uphill battle. Yes you find a ton of small inefficiencies all the time, and they are easily fixable. The problem is, there are several hundred people sometimes adding *new* inefficiencies.

Show threadSebastian SchönerSep 28, 2025
@aras @LarsThiessen @superluminal then again the "source available" nature of Unreal means there are potentially also more people looking at and fixing them. (That, and the average developer at Epic and even the average user of Unreal is much more technical than at Unity.)
Show threadLarsThiessen

@sschoener @aras @superluminal

True, but more people potentially fixing issues doesn't help if the owner of the code base doesn't have an efficient system to review and merge the incoming pull requests.
Not that I blame them, that's a complex task even many open source communities struggle with :/

Sep 28, 2025 at 9:16amWeb
Show threadLarsThiessenSep 30, 2025
@sschoener @aras @superluminal
I'll take everything back, the first of the two changes already got merged. Didn't expect to see a pull request that I submitted on a Saturday already being merged on Monday :o
Show threadSebastian SchönerSep 30, 2025
@LarsThiessen @aras @superluminal maybe it also helped that you wrote a blog post about it and got many eyes on it?
Show threadLarsThiessenSep 30, 2025
@sschoener @aras @superluminal
Yeah, I *strongly* suspect that being the case :D
I wouldn't complain if that motivated more developers to blog about their work, though. I could use some more reading material ;)