Fastest way to calculate primes in C#?

Question

I actually have an answer to my question but it is not parallelized so I am interested in ways to improve the algorithm. Anyway it might be useful as-is for some people.

Answer 1

You also should consider a possible change of algorithms.

Consider that it may be cheaper to simply add the elements to your list, as you find them.

Perhaps preallocating space for your list, will make it cheaper to build/populate.