I have been dealing with spikes in my latency for about a week..or should I say WAS dealing with it. If this scenario sounds similar to yours listen up. I would be playing at 90-110MS and all of a sudden jump to 400+ at times for no reason. The game would be choppy and my charcater would not attack or move at times. After 5 day of calling my ISP and submitting a ticket to blizzard I went on my own and looked for a solution.

I found a website call fixmylag.com. I was hesistant at first, but it turns out to be legit and I have been running the program while playing Diablo for 2 hours now with no hitch in gameplay at all. SMOOTHE AGAIN!!! It does cost money to download the program, but $30 for 3 months seems worth it to me. The program also allows you to use it on PS3 and XBOX systems. So you can get more bang for your buck if you are experiencing lag issues.

FIXMYLAG.com