Unreal Engine 5 has some powerful new features like Nanite for high-detail geometry and Lumen for advanced lighting, but these can require more resources and potentially cause FPS drops or performance fluctuations on less powerful hardware. If you don't need these new features and your goal is to achieve high FPS on older devices, Unreal Engine 4.27 might be a safer choice.
Generally, UE4 is more stable and has lower system requirements, so if you're targeting older hardware, it could provide more consistent performance with fewer fluctuations. Unreal Engine 5 tends to be more resource-intensive, especially with features like Nanite and Lumen, which, even when not used, can contribute to a higher overhead. So if you need stability and predictability in FPS, UE4.27 could be better.
However, if there are specific assets or features in UE5.3 that you need, you can disable Nanite and Lumen to reduce the performance burden, making UE5.3 more like UE4.27 in terms of resource usage. This might help increase FPS or at least stabilize it.
The best approach is to test your project in both engines. Try to benchmark the performance in different scenarios to see how much it fluctuates and whether it meets your performance requirements. This way, you'll have a better sense of how each engine version behaves on your target hardware and whether UE5.3 or UE4.27 is the better choice for your needs.
