First load/compile of the day extremely slow?

Hello, the first time I launch unreal for the day takes about 25 minutes. (binary UE4, from the launcher)

Launching the game after that (from crash or manual restart) is about 30 seconds.
Same happens with compiling the c++. First compile takes up to 15 minutes even without any changes.

I heard somewhere this shouldn’t happen and I may be losing some cached files when I restart my PC.

Is there any way to fix this?

Thanks!

Compiled Unreal engine has extremely large .pch (precompiled header files). If these files are not in your RAM cache, compiler will spend relatively long time loading them into the memory. To avoid this dependency I’ve put all Unreal engine files to SSD, this eliminated any build time dependency from number of builds before now.

Hey Gildor, I don’t understand how moving the unreal engine to SSD eliminated build time dependency. Do you mean it’s just much faster now because of SSD? Or were there also some other steps you took? I don’t have an SSD so I’d love to know if it’s possible to fix without one.

Hi. I didn’t mean “eliminated build time” dependency. It eliminates time required for OS to read huge amount of data from HDD to RAM, which causes very slow build for the first time after reboot. It is not possible to “fix” this, just because OS must read these data from disk. When you’re building project again, you’ll have these data in RAM cache, so compiler will not spend any time reading data from disk.