There has been a problem for a very long time. CUDA 11 is slower than CUDA 10.
GitHub - issue
My 5-year-old laptop with an Nvidia 940M (CUDA 10) video card works better than the 3070TI (CUDA 11) - This is nonsense!
For such a long time, this has not been fixed, that I already regretted that I bought the 3070ti