Forza Horizon 3 stuttering issues are seemingly all about the EFS DRM which Microsoft, Turn 10 and Playground Games have implemented into the Windows 10 PC version of the game. As reported on Reddit, that DRM would be requiring a lot of CPU work and this would be why even high end rigs have difficulties in handling it.
“Yesterday, I’ve captured a usage on my CPU and GPU, and found interesting thing, when CPU has 100% a lot of stuttering appears and GPU usage lower fluctuates at 50-80%. Stutters mostly appears in a city and mostly at the fast speed, when the game loads a lot of assets simultaneously,” Reddit user dkhavilo reported.
“Then I’ve navigated to a folder where game is installed and found that game folder uses EFS, which AFAIK uses AES256 encryption. Having EFS is ok for sensible documents, not the game files, because it requires a lot of CPU to decrypt.”
This report might be to be believed as Digital Foundry has previously discussed the topic without clearly finding out reasons why the game is running smoother at 4K resolution rather than 1080p. According to them, it looked like it was a a matter of anti-aliasing having a major impact on performances for certain configurations, but it looks more likely that the DRM in place is making those computers suffer so much.
Check out our Forza Horizon 3 PC Error guide for fix to stuttering, crash at startup, low FPS and many other issues.