I had exactly the same fault. The game played 100% in single player so I rules out the PC. I was getting online freezing and was unable to fire.
My pings were ok........turns out is was my daughter DOWNLOADING lots.
My problem was throughput or lack of it. If your using a wireless router is someone nabbing ya bandwidth.
David
My pings were ok........turns out is was my daughter DOWNLOADING lots.
My problem was throughput or lack of it. If your using a wireless router is someone nabbing ya bandwidth.
David

I'd done i twice and had given it up as a bad job. 

Cant get her off it now, I'm so lucky