Same issue. I'm using Avast 2015.10.2.2218. I was using Avast Free Antivirus. A few days ago, the program offered to give me a 21-day trial of Internet Security. I enabled it, and immediately the problems started. Tons of DPC Latency, audio and video skipping. I have an SSD with 32gb of memory on an AMD A8 so there's really no reason this should be happening. At first I thought maybe it was a Windows Update or a Chrome update, so I used Window Performance Analyzer to chase down the problem. The latency was being caused by the network drivers, WPA listed ndis.sys, tcip.sys and netio.sys as the culprits. I am using the latest driver available from the manufacturer for my Qualcomm Atheros 8151 NIC.
So I did some digging and found this thread. I ended the Internet Security trial, rebooted, and immediately the problems went away. I'm back to playing 24/192 audio with dozens of 64-bit Chrome tabs open - no problems at all, as before.
This is a real shame as Avast Free AV is a great product. I'm a freelance IT consultant, so I definitely won't be recommending my customers pay for Avast. Eset is the best paid option anyway, but of course it's much more than $20 a year.
It's really sad that this thread has been open for nearly two years, and no response from Avast, nor apparently any attempts to fix the issue either. Fail!