2 of 2 Fixed list & grammar

Is 8192 Diffie-Hellman overkill?

I've finally ran SSL server test on my server and was presented with:

This server supports weak Diffie-Hellman (DH) key exchange parameters. Grade capped to B.

So I tried to generate stronger using openssl dhparam 8196, but it didn't finished even after a day. So, two questions:

  1. Is it an overkill and is 4096 sufficient for now?

  2. Can I make openssl dhparam run on multiple cores?