Excessive latency with BT input devices?

I can only pass comment on the BT Magic Mouse. No lag, and very precise in use, particularly in select / drag functions. If you use eneloop rechargeable batteries, you get a good 3-4 weeks of intensive use before replacing them.

I can't pass comment on other BT stuff as at present I don't use any, but will shortly be buying a Magic Trackpad...

 

Yes, latency was an issue for a number of years with wireless products in general, and deservedly or not, bluetooth in particular. I had a couple BT mice quite a few years ago now that were noticeably laggy, and suffered from fairly low pointer update rate as well causing choppyness when moving the mouse.

What fixed it? The inevitable, general march of progress of technology. It's not really something that is fixable once a product is designed and manufactured; instead, newer products will be inherently better.

The magic mouse isn't quite as smooth and responsive as a corded mouse, but the difference is negligible for general use* as long as BT reception is good. On my Macbook I've had intermittent issues using the mouse with the BT antenna pointing away from the mouse (it sits in the plastic hinge of the notebook, due to the metal chassis acting like a shield), but recently I've not encountered any such episodes recently as long as I keep the mouse batteries in decent shape.

* "General use" doesn't include high-level gaming, where the magic mouse doesn't exactly shine. Pointer update rate is a bit of an issue when playing first-person 3D games, and the Magic Mouse can't detect both left and right mouse buttons being held down simultaneously anyway, likely making the mouse unsuitable for anything more demanding than Valve Software's Portal games.