Prime numbers generator
There's a lot to be improved here.  What you call dividers would be simply called primes.  This may have loosely been inspired by a sieve, but its inner mechanics are nothing like a sieve.  It's no surprise that performance degrades with larger numbers, and if you go too high, you may run into memory issues since the dividers (or primes) keeps a list in memory.

Performance should also suffer because you check every number from 2 onward.  You could check 2 to eliminate all evens first, and then only check odd numbers after that.

We discourage one line calls here unless enclosed in braces.  So change this:

if (divider * divider &gt; inputValue)
    return false;


To this:

if (divider * divider &gt; inputValue)
{ 
    return false; 
}


You may want to investigate using a sieve.  Here are old examples:

Sieve31, my sieve of Eratosthenes returning IEnumerable&lt;int&gt;

Sieve32, a simple 32 bit sieve returning IEnumerable&lt;uint&gt; using C#

Sieve32FastV2 - A fast parallel Sieve of Eratosthenes