Just wanted to drop by and say THANK YOU!
I have been having this DPC latency issue for almost 2 years now!!! I didn't find out about it being DPC latency until last thanksgiving when i finally got fed up with restarting my computer before each session (and about every 2 or 3 hours to keep it stutter-free)
Played around for awhile with LatencyMon and DPC Checker, and have been researching my top culprit (ndis.sys) for the last 2 weeks. Just came across this thread after searching for a possible relation to avast and ndis.sys, and modified my installation to exclude the firewall. Had DPC Checker running the entire time and watched my red bars completely vanish!!! Haven't restarted yet, but will do so soon and leave it running for awhile.
So far, my top highest executions on LatencyMon are dxgkrnl.sys, USBPORT.SYS, and nvlddmkm.sys, so 2 graphics related drivers and a USB driver. but nothing has broken the 1.0(ms) mark yet, which is a MAJOR improvement, and even with small spikes (still in the green on checker) I've had smooth audio/video playback while browsing the web and using utorrent.
By the way, I went as far as to disable my onboard NIC (realtek) and bought a TP-LINK ethernet adaptar, brand new with most recent drivers, and nothing changed prior to uninstalling avast's firewall.
OS is Windows 7 here, so the issue is not just isolated to a specific windows version. I've seen complaints with ndis.sys on 7, 8, 8.1, and 10 so far. Wondering if everyone was running avast...