iRacing Stuttering Fix on Intel CPUs: Unpark Your Cores Safely

If you have ever suffered freezes or stuttering in iRacing, you already know how annoying and harmful it can be.

Since the launch of Intel’s 12th gen, the American giant’s CPUs have used different types of cores in the same processor: performance cores and efficiency cores for background tasks. Because not all cores are normally needed at the same time to handle a given workload, that workload gets rotated between cores and, if one of them is in a parked state, the dreaded stutter or brief freeze can occur. This is especially noticeable on 12th to 14th generation CPUs.

The way to get rid of this extremely irritating effect in iRacing is by disabling core parking in Windows. Energy plans or other simple tweaks are not enough; you actually need to edit the registry and modify it:

1. Check if your cores are being parked
   Press Ctrl + Shift + Esc to open Task Manager, go to the “Performance” tab and click “Open Resource Monitor”. In the CPU tab, look at the individual CPU graphs and check if any of them show the word “Parked” next to the core name.
2. Open the Registry Editor
   Press Win + R, type regedit and press Enter. If prompted by User Account Control, click “Yes” to allow changes.
3. Search for the core parking setting
   In Registry Editor, select HKEY_LOCAL_MACHINE, then go to the top menu and click Edit > Find…. Paste the following string into the search box and click “Find Next”:
   dec35c318583
4. Change the ValueMax entry
   The search should take you to a key under:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\...
   On the right-hand side, double‑click the ValueMax entry, change its value to 0 (zero) and click “OK”. This tells Windows that 0% of the cores are allowed to be parked.
5. Restart Windows
   Close Registry Editor and restart your PC so the change takes effect. After rebooting, open Resource Monitor again and verify that none of the cores show as “Parked” anymore.

You can see the entire process in this video by David Cam:

As far as is known, disabling core parking is not dangerous in itself, beyond the impact on temperatures and power consumption. Everyone who makes this change does so at their own risk; we are simply sharing the information that is currently available.