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Help get Forza Horizon 6's stutter fixed

Forza Horizon 6 freezes for about a tenth of a second roughly once a second, whatever the settings, on every Mac we have heard from. In Apple's Metal HUD it shows as tall spikes in the frame time graph. The cause is in Rosetta, the part of macOS that runs Intel code on Apple silicon, so neither Highball nor Wine can fix it. Apple can, and every report that points at the same problem makes it more likely they will.

Five minutes, nothing to install, no Terminal. Open Feedback Assistant, paste the two texts below, press Submit, then share your FB number with us.

What is going on

About once a second the game's copy protection runs a check while the game waits for it. The check triggers about 2,000 CPU exceptions on purpose and handles each one itself. On a PC an exception takes one or two microseconds, so the whole check is over in a few milliseconds. Under Rosetta each one takes 15 to 60 microseconds, so the check takes about a tenth of a second, and that is the hitch you see.

We measured it on an M4 Mac mini with small test programs. The same exception costs about 1.5 microseconds in native Apple silicon code, about 15 under Rosetta, and about 32 under Rosetta when other threads are busy, as they always are in a game. Wine's own share is about 5%. We tried every setting we could find, real-time priority included, and the best of them shortens the hitch by about a fifth. Any game whose protection works this way is hit the same way. Forza Horizon 6 is the one we measured.

Why your report helps

We sent Apple a detailed report with the test programs and every measurement. Its number is FB25100017. Apple's own engineers suggest filing your own report that names the original one, so the two get linked, and the number of linked reports shows Apple how many people a problem affects. You do not need to be a developer or run anything. Apple does not promise anything, so think of it as adding your voice.

Before you start

Feedback Assistant only works with an Apple Account that is in Apple's free Beta Software Program or registered as an Apple developer. If yours is in neither, join the Beta Software Program at beta.apple.com with your usual Apple Account. Joining does not put a beta on your Mac. Betas only arrive if you pick one under Beta Updates in Software Update settings, so leave that set to Off. If you would rather not join, Apple's macOS feedback form takes the same text without any sign up, though a report sent there cannot be linked to ours.

Send it

  1. Open Feedback Assistant. It is already on your Mac, so press ⌘ Space and type its name, or use feedbackassistant.apple.com. Sign in with your Apple Account.
  2. Press New Feedback and choose macOS.
  3. For the area, choose the one about Rosetta if the list has it. If not, choose Something else not on this list.
  4. For the kind of problem, choose the one closest to an app being slow.
  5. Copy the title and the description below into the form, and fill in your Mac and macOS version.
  6. If it offers to collect diagnostics, let it, ideally while Forza is running and stuttering. They go to Apple only. A short screen recording of the hitch with the Metal HUD on helps too.
  7. Press Submit. Feedback Assistant shows your report's number, which starts with FB.
  8. Share that number with us, as the next section explains.

Title

Forza Horizon 6 stutters about once a second under Rosetta (same as FB25100017)

Description

Same issue as FB25100017, please link this report to it.

Forza Horizon 6 (Steam, running through Wine with Highball) freezes for about a tenth of a second roughly once a second on my Mac. The game's copy protection runs a check about every second that triggers around 2,000 CPU exceptions, and each one is about ten times slower under Rosetta than in native code. FB25100017 has test programs and measurements.

My Mac: [model, chip and memory]
macOS: [version]
What I see: [for example, a hitch every second in menus and while driving]

Share your FB number

Post your FB number with your Mac and macOS version in the GitHub thread or on our Discord, whichever you use. We add the numbers to FB25100017 as they come in, so the engineer who has our report sees every player behind it in one place. Nobody else can see your report, so this is also the only way we can count them.

What to expect

Apple rarely answers reports like this one. If yours comes back marked as a duplicate, that is good news, it means it was linked to the main report. Nothing will change overnight and Apple promises nothing. It is still worth asking, because Rosetta is what runs every Windows game on a Mac today. If Apple answers, we will say so here.

Questions

I don't play Forza Horizon 6. Should I report anyway? Only report what you see yourself. If another game hitches the same way, describe that game instead and still name FB25100017.

Do I need to run anything? No. If you are comfortable with Terminal, the test programs and the full text of our report are on GitHub, and the numbers they print on your Mac make your report stronger.

What does Apple get? What you type, plus diagnostics only if you agree to attach them.

Where do I ask a question? In the GitHub thread or on our Discord.

Last updated 9 October 2026. Our report is filed and Apple has not answered yet.