Nested Parallel.For() loops speed and performance

Question

I have a nested for loop. I have replaced the first For with a Parallel.For() and the speed of calculation increased.

My question is about replacing the

Answer 1

It again depends on many scenarios,

1. Number of parallel threads your cpu can run.
2. Number of iterations.

If your CPU is a single-core processor, you will not get any benefits.

If the number of iterations is greater, you will get some improvements.

If there are just a few iterations, it will be slow as it involves extra overload.