I doubt anything UX based will get slower. DWM etc use the GPU to draw everything, and almost every PC is on at least a SATA SSD now compared to when 10 came out, with the vast majority of machines on NVMe boot drives especially laptops.
The only things that will realistically change is how smooth animation transitions are. Like those small frame drops due to lack of optimisation will get fine tuned over time as GPU drivers mature and DWM backends get even more efficient.
in all these years I have had the same base install of Windows since Vista and have done an in=place upgrade. I have only ever noticed Windows animations and speed get better over time even though there have been more animations and stuff added to each new Windows. Each major gen I've upgraded something major too like GFX or SSD or added more RAM.
The only things that will realistically change is how smooth animation transitions are. Like those small frame drops due to lack of optimisation will get fine tuned over time as GPU drivers mature and DWM backends get even more efficient.
in all these years I have had the same base install of Windows since Vista and have done an in=place upgrade. I have only ever noticed Windows animations and speed get better over time even though there have been more animations and stuff added to each new Windows. Each major gen I've upgraded something major too like GFX or SSD or added more RAM.