Magic mouse 2 lag after upgrading to macOS X Big Sur.

Delete the preferences from the ~/Library/Preferences/ directory

• com.apple.AppleMultitouchMouse.plist 
• com.apple.driver.AppleBluetoothMultitouch.mouse.plist 

Then your problem is gone.

I've resoled this problem with my 21.5" iMac 2017 with macOS Big Sur 11.2.3

In my case, this had almost nothing to do with the mouse, the mouse was just the most visible effect of the root problem.

I started watching my activity monitor like a hawk, I noticed something was taking up nearly 30%- 40% of my processor all the time, even with no programs open. It was the Window Server. I started digging into what could cause the Window Server to eat up so many resources. I have two external 1080p monitors hooked up to my iMac via USB-C, the primary iMac display was set to be scaled so items would be roughly the same size across the 3 displays. Well if you go into your Display scale settings, adjusting to anything except "Default" causes a new notice to appear: "Using a scaled resolution my affect performance".

So the Window Server was bogging down EVERYTHING to scale my primary display and push two external displays, and the Bluetooth mouse performance just happens to be one of the first things to go when your system is hungry for more CPU.

I've been running 3 displays on this iMac since at least Mojave without issues, I'm not sure what "advancements" Apple made to cause this to happen but I'm happy to have a working computer again.

Hope this helps!

Hi ricmoura,

Welcome to Apple Support Communities. We understand that your Magic Mouse 2 is not as responsive after the update to macOS Big Sur. We'd like to help.

You mentioned that you also are using a bluetooth keyboard. Are you having those same issues with the keyboard? If you disconnect the keyboard, do you see an improvement with your mouse? Do you have another mouse you could test to see if this is isolated to the Magic Mouse 2?

If you are still having issues after testing it without the keyboard or with another mouse, booting into safe mode can help. This resource can help you get into that mode:

How to use safe mode on your Mac

Let us know how that goes after you complete that step.

Certainly sounds as if it's something else in your setup, given that two different MacBooks had the same problem. Radio interference is the likely culprit. Quick test: turn off the Mac's Wi-Fi, see what happens. Then turn off the router, and see what happens.

I have deleted the 2 files and it didn't work, the lag was still very bad, BUT my internet also started to become non responsive at this time. I turned of the wifi and the lan connection, waited 10 sec and turned it back on and voila I have no lag on my mouse. I don't know if this is a solution but the internet connection or the hardware/software that controls/connects to the internet definitely had something to do with this issue on my Mac mini M1 and Magic Mouse 2 that lagged.

It could be Wi-Fi interference. If your router has a "5G" option, try turning it off; alternatively, try using 5G exclusively.

Yes, same issue here - Mac Mini in this case, OS 11.2.3, Magic Mouse that worked perfectly under prior OS. Cursor movement is irregularly very slow, and sometimes the Mac thinks I'm holding down the ";" key, even when the keyboard is unplugged.

Deleting com.apple.driver.AppleBluetoothMultitouch.mouse.plist is a temporary fix.

com.apple.AppleMultitouchMouse.plist doesn't exist on my system.

This problem started for me immediately after patching to Big Sure 11.2.2. I have to Magic Mouse and they both are behaving poorly, jittery, and sometimes complete unresponsively under 11.2.2. I have another MacBook Pro that has is still running 11.2.1 and both mice work fine when attached to it.

This worked for me as well. Thank you! I just upgraded to 11.2.2

Hi friend, same but same identical problems with this MagicMouse.

After much hope lost on updates to fix this, I bought a Logitech Mouse and Keyboard combo (100usd)

I guest what, keyboard experience improved due to size and form, and mouse experience revealed too. It has a metallic central scroll wheel, that allow you to move up and down very fast. That for my coding is gold.

Keep looking for the correct update to fix the mouse issue ...

The mouse may be put in a little rough surface. Put a mouse pad or something smooth.

Big Sur is no longer be called Mac OS X

X means 10

I have this same issue and am losing productivity too - I can't seem to find those preference files you've mentioned above though? Any help is much appreciated.

I'm running a 16" 2019 mac book pro with magic mouse 2 and a magic keyboard. Both were working fine before Big Sur, so I'm not changing hardware for that! hah.

I have this same issue and is very annoying... and hit my productivity a lot !

Tried all recommendations and those solve momentarily the problem.

I finally connected a wireless logitech mouse and is working perfectly.

I can't believe how a 20 usd mouse, is working and a 80 usd it si not....

Can someone guide me onto a real solution !

I bought a brand new MacBook Air top of the range Aug 2020. Countless issues inc crash on sleep, frequent Wifi drops and slow, stuttering mouse from time to time. After countless hours, countless reinstalls, countless support calls etc - sent Mac back to Apple to fix. I had to buy ANOTHER Mac as I rely on it for work. Just updated the new Mac (which I reset) telling me they could not replicate any problems (really?!) - so I updated to BigSur, and within 5 mins, a slow stuttering mouse. Not permanently, but every now and then, just to remind you it is there. Lasted 5 seconds or so. I didn't experience this on my other new Mac (both are Intel not M1) - though both crash on sleep, and both drop Wifi in a random fashion.

I'm a fully converted Apple user for 10 years now - but THIS REALLY ***** and reminds me of Windows bollocks.

The resolution provided only works temporarily, in my experience for maybe a day or two.

I'm having this issue on my 2017 21" iMac and It's annoying as h*ll. Intermittently the mouse will go from having excellent response times to taking between half a second to a few seconds to react to my inputs. Meaning I move the mouse.... wait a few seconds (actually a 1 - 3 seconds!) and THEN the mouse reacts on the screen.

This only started happening with macOS Big Sur. Really wish Apple would figure out what's going on here, this is not an uncommon issue.