Slow Compiler Time


I am almost done with bulls cows game and I have been running into this slow compiler time problem recently.

I also just deleted OneDrive so I am not sure if this is related to the problem here.

Here is a copy of my message log:

Is this new or has it always been slow?
Are you running Unreal Engine on a SSD and is the project on an SSD as well or using a standard hard drive?

The SSD, aside from CPU and GPU, is the biggest cause of slowdowns with Unreal.
Other than that, having at least a 4 core CPU is useful and I see it ran 12 processes so assuming 6+6 threads?


I am using an SSD on my computer but I am not sure how to check to see if Unreal or the project is running on it. I can probably assume that it is.

My CPU is using 6 cores. I am not sure if that answers your question or not.

It does. Usually C++ projects can take a while to build, and truthfully 60 seconds isn’t a massive amount of time. Small changes on small projects may take 10-15 seconds and large changes across many files longer.

I just looked at your screenshot again and noticed you’re running in the one drive folder on your c drive. This would be a big no-no simply because as the compiler writes to the intermediate folder, your machine is syncing to one-drive. This will seriously slow down your compile times.

Create a folder on your C Drive, Projects or something, and work within that folder. This should help with performance.

I wonder if people expect that a game can be shown as one works on it in the PIE editor then don’t understand why there are compile times and why it takes more time then they expect?

Compile times, typically someone complains about it, but I’ve not seen that so much as I see it here.

But considering he just deleted one drive, I don’t see how it would still be an issue. Still, One Drive is not a good way to go about code management as it was never meant to work with code.

Well, if you are new to C++ and used to working with, say, Unity and C#, then this is non-existent. I’ve seen the compile time of C++ as a reason for people to switch to Unity and honestly, I can see why since even with huge Unity projects, the delay is no more than BP in Unreal.

If people are also used to scripting languages such as JS, Python or other languages along those lines, this is also a non-issue.

For those used to developing in C++, clock speed and CPU Cores along with performant disks (not actually that critical for regular C++, but UE is essential) can make a huge difference.

My old office PC, 2010 and 6 core Xeon outperformed a 2016 4 core Xeon because A, it had a higher base clock speed (3.4Ghz vs 2.4Ghz) and B it was threaded. The fact the 4 core was newer and so inherently faster made no difference even though it had a SSD because it lacked cores, threading and cycles ie clock speed, combined caused it to be slow.

Laptops, usually are less performant as they usually have low clock speeds and even a fast SSD won’t make a difference there. Switching power saving to performance can help but often a Laptop processor, even if it says i7 for example, will have a 2-3Ghz Clock speed and often less cores. A colleague got a laptop and it has 6 cores, threading and top clock speed of 2Gz! The same desktop class CPU has 8 cores and 3.7Ghz clock which is double the speed almost without extra cores. ( my personal PC has a base clock of 3.8Ghz but during UE compile boosts to 4.65Ghz - compile times are usually under 10 seconds for most projects - it was built for UE and C++ in mind)

So there are a lot of factors here.

Generally, laptops are non-starters for heavy development unless you get a high spec gaming laptop and you have about 2K or more to spend - a shop-bought one from a Best Buy, Currys or something just won’t cut it. They can do it but they will be slow. Fine for internet access and Word processing, even scripting or C# development but not C++.

Personally, I enjoy BluePrint development because of the lack of compilation and slower machines are happy.

You cover so much that I can’t think of anything to add to that :grinning:

Personally, I’m fine compiling under 10 minutes let alone 1 minute or so. But, yeah, I have a laptop where a full compilation takes about 2 hours needed three times in a row for a complete compile compared to something like 12-16 minutes each on desktop. The hardware has a lot to do with it.


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