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 ran on multiple cores?