Q: Sluggish/Jittery Magic Mouse after Yosemite

Update: Unfortunately I've just discovered that using my MBP open (as opposed to Clamshell) DOESN'T help. The lagginess occurred while the MBP seemed to be under increased memory load, as someone else suggested, this might be a memory leakage problem??

I have tried the magic mouse on a friend's MBP and it worked fine for a good hour of testing.

Could this be a "Continuity" issue?  Try turning off all the continuity features (Handoff, Phone calling, SMS and Instant Hotspot)?  I would give it a try but the problem happens infrequently for me.  I'll try to remember to try the next time.

I did try deleting the Bluetooth PAN in the network settings on my Mac Pro over the weekend when I experienced this problem but that did not make any difference.  I did not do a reboot though now that I think about it ... I guess I should reboot and see.

I see the same issue, if I am compiling code, watching HD video, opening other windows the mouse becomes sluggish, I really hate it!

I am running Yosemite 10.10.3 on a 2012 - 27" iMac. Same problem with lag & magic mouse cursor that jumps around - typically to the bottom right corner of the screen. Problem first cropped up after Yosemite was installed. Has progressively gotten worse. I have tried virtually every suggestion on the various threads I've read. Some work for a while (typically a few minutes or less), others have little or no effect. Apple store found no problems. Definitely impacts workflow. As photographer, Apple has been a standard for some time - this is convincing me to start to seriously look elsewhere. It is truly amazing that Apple is so quiet on this matter. Let's hear it for customer service. Currently only solution is to use USB mouse. Sigh.

Exact same issue also. Im going out today and purchasing a brand new magic mouse. It seems like the mouse isn't as responsive or snappy anymore.

Don't expect much to change with a new mouse (assuming all of us are having the same problem), I've tried my magic mouse on a different MPB and it works fine, I've also tried using a Microsoft bluetooth mouse on my MPB and it has the same problem.

I recently had my logic board replaced under warranty as the graphics card went (a known issue on early 2011s) and was told that may fix the bluetooth problem - it didn't. The only other solution I was told to try was wiping the MBP and reinstalling everything from scratch, since it is most likely a software issue. I'll report back.

Thanks for that feedback, I might hold out on buying the new mouse. My symptoms are mainly around the responsiveness of the mouse and the occasional disconnect/reconnect.

Unfortunately I'm on the beta program  (which I'm quitting once the next production update is out).

For what it's worth, these 3 steps solved the problem of the jittery mouse cursor for me: switching bluetooth on and off in System Preferences, disabling Handoff and finally, putting my mouse on a mousepad.

Thanks for your idea, I disabled handoff & rebooted bluetooth. It made no difference & i think the mousepad might just be a coincidence.

This may help finding the source of the problem: I am having exactly the same problem with a Logitech M570 wireless trackball. That suggest it is not the mouse itself that is at fault.

I had the jittery mouse problem and tried all the suggestions on his list. Just installed update 14E26a to Yosemite and have a steady mouse for the first time on this computer which came with Yosemite installed. Hope it stays nice and calm.

I cannot tell you have many different solutions i have tried to the same problem.  The ONLY thing that worked for me was to use my 5GHz band on my Airport.  I don't like using that band because my signal isn't as strong (too many walls), but the problem is completely gone now.  So it really appeared to be a combination of 10.10, 2.4GHz, and BT.  I hope the next OS addresses this problem!

After upgrading to 10.10.3 on my 2014 Mac Pro, my magic mouse started disconnecting for no apparent reason (no other bluetooth devices in the house, fresh batteries, refreshing mouse setup, etc.).  I finally threw in the towel, dug my old wired Apple mouse out of the closet and viola, problem solved (sort of).  Funny thing, though.  My wife's iMac is not on 10.10.  Her magic mouse is fine.  And my magic mouse works fine on her iMac as well - so this is an Apple 10.10 issue and they apparently aren't interested in addressing it.  I wish I could go back to 10.10.1 - the mouse worked fine then, and my Mac Pro booted almost instantaneously - I am not impressed as much with Apple as I used to be.

Incredible, but immediately after disabling Wifi, my Magic Mouse connected and worked like a charm. Unfortunately, after enabling it back again, the issue appeared again.. This is the weirdest thing ever!!! come on Apple!!!

I am having the same sorts of problems on a two-year-old iMac with current updates of Yosemite. At first it was just an occasional annoyance, but now it happens way too frequently. My symptoms include one that I didn't see mentioned elsewhere in this thread - often a single mouse click seems to register as a double-click. I was trying to edit some photos yesterday and it was just unusable.