UE5.1 why is my project taking way longer to load?

Hello, We are moving our project from 4.26 to the latest 5.1 . Most of the game transferred just fine but can someone explain to me why the startup times are absolute trash on UE5? Our project would seem to load in less than 5 min in 4.26. but in 5.1 its taking closer to 20 to 30min? why is that?

Is there any way to speed it up? Also if it helps everytime i launch the project in 5.1 it seems like it has to recompile all the shaders like it was the very first time opening it.

Please help!

Hey there @l_l! Combining this with your other post, there may be an issue with the shader cache, as you shouldn’t have to do a full rebuild every time you launch it unless there were changes to the shaders in the meantime. Could you back up your project then move these folders and let them regenerate and after the first launch let me know if it’s gotten better?

I’ve been seeing issues with migrated projects taking longer than native projects to load.


hey sorry this didnt work. any other ideas?

In Unreal Engine 5, the startup time can be slower due to several factors. One primary one is that the engine has been re-architected to support features such as dynamic global illumination and ray tracing, which can increase the time needed to initialize the engine and load assets.

There are a few things you can try to speed up the startup time:

  • Optimize your assets: Remove any unnecessary assets, optimize textures and meshes to reduce memory usage, and make sure your materials are optimized for performance.
  • Try to use smaller project settings, such as a lower resolution or fewer light sources.
  • Use the Unreal Engine Profiler tool to identify bottlenecks in your project and optimize those areas.
  • If you have a lot of custom plugins and code, consider disabling them temporarily to see if that improves the startup time.

It’s worth noting that the startup time can vary based on the complexity of your project and the hardware you are using. It’s recommended to test and optimize the solution accordingly and make sure to test and validate the performance on the target hardware.

I noticed an increase in startup time when moving from Unreal Engine 4 to 5.

Do you have to always build shaders when you start your project?

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