Found out that the gradual rise in DPC latency is actually due to the "real time protection" scanning by Microsoft Security Essentials AntiMalware Program.
If you are running MS Security Essentials, this is most likely your issue. There is no current fix other than disabling "real time protection":
MSE gradually increases DPC latency when there are high network activity
I tried a lot of the other suggestions posted here without luck. Turns out, MSE was the source of my problem and it was mostly affecting iTunes. I didn't like the idea of disabling real time protection (which also generates lots of warnings by the software). Instead, under MSE Settings>Excluded Processes I added iTunes.exe and iTuneHelper.exe. That eliminated the popping.
Hope this solution helps others.
My Computer
At a glance
Windows 7 Pro x64Intel Core i5 650 @ 3.20GHz6.00 GBATI Radeon HD 5450
- Computer Manufacturer/Model Number
- HP s5580t
- OS
- Windows 7 Pro x64
- CPU
- Intel Core i5 650 @ 3.20GHz
- Motherboard
- MSI 2A9C: Intel PCH H57 chipset
- Memory
- 6.00 GB
- Graphics Card(s)
- ATI Radeon HD 5450
- Sound Card
- Realtek High Definition Audio: Driver Version 6.0.1.6053