Logitech wireless keyboard lag
Solution 1:
Definitely receiver placement. I have my laptop mounted on the back of my big monitor and use the laptop monitor as a second screen that sits on top of the external one. If I put the receiver on the left USB everything gets wonky. On the left it sits between the HDMI and aux cables and I think that is part of the problem with the additional distance. But if my laptop is just sitting on my kitchen counter, I can use the mouse/keyboard from 10 feet away no problem.
Also make sure your phone is not near (12 inches-ish) or directly between keyboard/mouse and receiver. When mine lags, I just mindlessly look for my phone and move it and all is good again.
I think it's the bluetooth on the phone but phones kick out a lot of junk so not sure. I'm not going to start turning BT off just to resolve this so never tested this theory.
Solution 2:
I'm not entirely sure about placement of the receiver as much as the bus it physically on. I was having similar issues - erratic behavior with a MX Performance mouse under 14.04. Tried lots of suggestions including upgrading to 3.19.0.xxx kernel, little seemed to work.
What I do recall was the receiver was on one of the "ports on the back of the machine".... looking into that It was worse, attached to an unpowered USB hub with several other devices. I simply moved it to a "front panel" port and it hasn't crapped out since. Plugging an ordinary corded mouse into the machine seemed to work fine - and at that point I was pretty sure it wasn't driver related.
Solution 3:
Another user reports that the positioning of the receiver could make a difference (see https://askubuntu.com/a/589132/89042).
I just tried moving the receiver to one of the USB ports in the front panel of my desktop PC and it seems to have improved (I have tested it for only few minutes so far, though). Mine is a Microsoft Sculpt Ergonomic Keyboard/Mouse combo.
Solution 4:
I've had the same problem. It turned out that it was due to a USB hub that I'm using. If I plug the keyboard's USB receiver directly into the computer it works without lag or delay. No idea why it wasn't a problem with Windows. This just in case someone else comes across this thread with the same issue.