I want to quickly summarize a topic that I ignored to a degree. This in respect to how Chaos affects general traces and collision handling.
I set up a simple test scenario where I was looking at the cost of the CMC (for its computation in traces and sweeps) on 4.27 PhysX and 4.27 Chaos, this before comparing against UE5.
Results goes as follow, per CharacterMovementComponent when moving:
PhysX 4.27 0.065ms
Chaos 4.27 0.09ms
UE 5.4/5.5 0.10ms
While these numbers may look similar, isn’t really the case as Chaos 4.27 is 29% slower than it’s PhysX counterpart. This talks a lot about the general performance regression we get from the physics, not for simulation, but for general traces, queries, sweeps,etc.
While 5.5/5.4 is at 35% slower than 4.27 PhysX, this small extra overhead should be coming for the Larger Unit values (so there’s is an answer to the LargeWorldUnit performance question). At the same time it doesn’t look like there has been a meaningful performance upgrade on Chaos since back in the UE4 stage for that type of logic.
After all of these findings I find myself more confident in using Unreal 4 for some projects. In fact at a point I was working in a online shooter title on 4.27 with RTXGI(for some reason RTXGI was broken in UE5 and had performance issues).
I think UE4 is a viable and sensible option that is available, and it should be given appropriate consideration when taking a decision as it’s truly different from UE5, not just an outdated version of something newer.