Recent games made in Unreal Engine 4 on PC have had intermittent stuttering issues, and it appears that Epic Games is looking to resolve the issue with a major update to Unreal Engine 5. The situation with stuttering has not been getting better with existing games developed in Unreal Engine, but there’s hope that things may be changing.
Digital Foundry’s Alex Battaglia had the opportunity to attend an open Q&A on the Unreal Engine website, where key people involved in the development of UE5, including its prominent features like Lumen and Nanite, were answering questions regarding Epic Games’ latest game engine.
Alex took the opportunity to ask a question regarding stuttering issues in existing Unreal Engine games. He pointed out to the dev team that, based on his experience, the engine was very single-thread limited. In addition, he brought up the shader compilation stutter issue in both Unreal Engine 4 and Unreal Engine 5 games on PC.
In response, a rendering programmer working on UE5 responded by saying that the dev team is actively trying to improve things with regards to this issue. A solution is currently in development phase with some local prototypes, but they hope to deliver an automated Pipeline State Object (PSO) gathering system at run-time, which pre-caches all PSOs that are required by the game. The pre-cache request will be handled as soon as an asset is loaded into the background.
The UE5 dev explained that through this new PSO pre-caching system, all the possible needed PSOs will, therefore, be collected. This will also include cascade and niagara effects and all possible light and shadow etc. Currently, the dev team is focusing on providing this fix to future shipped Unreal Engine 5 games in order to test whether its effectiveness in resolving the issue. However, they are hoping to extend it to the editor as well at some point.
Alex speculated that this solution may be similar to the asynchronous shader compilation method that developer Nixxes had incorporated into the PC version of Horizon: Zero Dawn once had taken over the project post-release. The game had launched with stuttering issues, which were later resolved by pre-compiling shaders. It wasn’t quite an ideal solution, but did its job for the most part. However, Nixxes later stepped in and incorporated a system where shaders were asynchronously compiled in the background a few seconds before they were needed by the game. This was a far more elegant fix for the stuttering issues plaguing the game at launch, and it appears that the dev team at Epic Games is working on a similar system for Unreal Engine 5 on PC.
Previously, we predicted that a potential PC port of PS5 exclusive Returnal may suffer from stuttering issues. Currently, it’s unclear whether Epic Games’ new solution can be retrofitted into Unreal Engine 4. If that is the case, the game, which runs on UE4, may run in a better state than we had expected.
