However, on my Mac Pro 4,1 (2009), cursor control has been spastic, making use of the Magic Mouse frustrating. Concurrently connected Apple Bluetooth Trackpad and wired Mighty Mouse both work normally, thus suggesting that it wasn't either the cursor control subroutines or the Bluetooth system at fault. I've kept all of them connected for years, switching around for either better cursor control or better scrolling.
Periodically, I'd look for solutions to the oft-reported problem, but none of the fixes I attempted had any effect.
Then I found this blog entry: MAC PRO 2009 BLUETOOTH FIX
And was immediately convinced that this blog's author had identified the true culprit: that the Bluetooth antenna location inside the aluminum case of the Mac Pro made for very poor signal propagation (my mousing surface is 10" from the top-front corner of the Mac Pro, and perhaps 30" from the OEM Bluetooth antenna's location inside the case). I liked the sound of the author's "BLUETOOTH FIX USING ORIGINAL BLUETOOTH CARD" solution, which mounts an aftermarket antenna on the outside of the Mac Pro's case.
As of January 2018, I found that Amazon stocks a 2-pack of both the appropriate antennas and the prescribed "pigtail" antenna cables for only $10US:
- (2) 6dBi 2.4GHz/5GHz Dual-Band WiFi RP-SMA Antenna
- (2) 35cm U.fl / IPEX to RP-SMA Antenna WiFi Wireless WAN Pigtail Cable
The brand name listed is "Highfine."
The fix is somewhat involved, requiring removal of the Mac Pro's CPU daughterboard and graphics PCI card. The solution also requires some real estate on a PCI mounting plate - the blog article specifies drilling a hole in a blanking plate, but all my PCI slots were populated. I chose to remove an infrequently-used adapter card for a video-acquisition box, but if I were to re-install that, I'd probably add the antenna to a USB 3 adapter PCI card. Fishing the pigtail cable through to the Bluetooth card, and actually working with the tiny U.fl connector can be challenging.
Problem solved! The Magic Mouse now works like a . . . mouse! Performance is fluid and consistent. It was totally worth the effort.