Over the course of the past 2 years, we’ve shown you many ways to optimize your PC: from turning off autostart programs, to turning off entire programs and even tuning netbooks for best performance. Unfortunately, if your PC or laptop is still painfully slow, you might be dealing with “DPC latency” issues – and that can mean a loss in performance much greater than could possibly be caused by any other problem. In this blog post, we’ll figure out if your PC is suffering from an unacceptably high DPC value, what this means and how you can troubleshoot it.
What is DPC?
Deferred Procedure Calls allow programs to queue up actions to be performed extremely quickly by the CPU. Until these DPCs aren’t executed, the computer comes to a halt (for a fraction of a second). Here’s an example of where this is important: Video playback! Obviously, both the audio and video has to show up on your screen almost instantly – the data needs to be read from the disk and each frame needs to be rendered in real-time. The same thing goes for audio and even your mouse cursor. So, some drivers and processes make use of DPC to deliver high-performance and instantly visible results.
However, if your PC is suffering from a high DPC latency, you’ll immediately see laggy, jerky performance, audio dropouts, glitches, stuttering etc. Those issues are mostly caused by drivers, but processes may also be the root of the problem. Fortunately, there’s a tool that checks for high DPC latency and can easily help you solve it.
The DPC Latency Checker
DPC Latency Checker, developed by TheSycon, shows a graphical representation of the current DPC:
As you can see, this system is suffering from a 1ms (1000us) DPC latency and never goes below that value. Plus, it regularly spikes to between 3 and 4ms. On a well-optimized and problem-free PC, this value should never go higher than 500us. If it does, you’re basically wasting precious PC performance. What’s the source of this? There may be several factors that cause an unusually high DPC:
1. Update Bad/old Drivers: In about 90% of all cases, drivers are the root of this problem. I suggest updating all drivers on your system; that includes Wi-Fi adapters, LAN adapters, USB host controllers, Bluetooth receivers, sound chips, graphics and last – but definitely not least – the chipset controllers. As I’ve written in the past, there are several very good sources for the latest and greatest drivers – also, DO try out beta versions of drivers.
2. Disable Devices: To figure out which of your devices may be the cause for these high DPC spikes, I suggest you disable all non-essential devices one by one and keep an eye out for changes in your DPC latency. To do that, go to “Device Manager” (WINKEY + R, enter “devmgmt.msc”). Right-click on a non-essential device, select “Disable” and watch the DPC Latency Checker graph:
Beware: You can’t disable everything, so focus on non-critical entries such as Wi-Fi, sound or Bluetooth and stay away from “System devices”, “Processors” or anything that might render your PC unusable (e.g. don’t disable keyboards/mouse).
3. Turn off 3rd party programs: Some 3rd party tools may be responsible for an unsually high DPC latency. To turn them off easily, just use our very own TuneUp Program Deactivator. Check out this blog post that explains, how Program Deactivator works and how it may help you get rid of DPC issues. Just turn off ALL (!) programs and see if DPC Latency Checker shows any change.
4. Turn off hidden startup programs, explorer plug-ins, browser extensions and more: Now, that you’ve used TuneUp Program Deactivator to get rid of essentially all 3rd party programs, it’s time to turn our attention to hidden startup programs and extensions. Check out this guide to both detect and disable unnecessary background activity.
5. Update your BIOS: Go to your PC makers website and try to find instruction on how to update the BIOS. If that doesn’t help, nothing will.
Using all of these solutions, we were able to lower the DPC latency significantly. As you can see from the graph above, the baseline (idle) is very low – only during extreme network spikes and hardware activity is DPC Latency Checker showing an increase.
If all of those four solutions, didn’t help: Reinstall Windows! Now, from the start make sure to run DPC Latency Checker. If the issue exists right from the start – without any drivers or applications running – it might be wise to check back with the PC manufacturer or (if you’re savvy enough) physically yank out hardware that you don’t need, such as additional hard disks, Blu-ray drives or a sound card; of course, that’s only an option if you’ve got a good old desktop PC.
17 Responses to “Poor Jerky Performance: Fixing Unacceptably High DPC Latency Issues”
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