I'm trying to see if I'm the only one with this issue. I have an Intel Haswell I5 NUC with 8GB's of Ram and a 120GB Mushkin SSD connected by ethernet and running Windows 7 X64. Everything is functioning fine except the Logitech Wireless keyboard and touchpad ( K400) with unifying receiver. Basically, it stutters on movement, especially when that movement is video related to anything in any browser. I thought at first the keyboard might have been faulty, so I switched it out with another all in one keyboard ( logitech K700 ) which came from a google TV Logitech Revue, but the problem persists. So, I switch unifying receivers, replace it with the other keyboard and plug the unifying receiver into a different USB port in the front, but the tracking on the touchpad continues to stutter while moving across the screen. Decided to try the all in one keyboard / touchpad in my I5 Haswell laptop. No problems whatsoever under the same circumstance. The kicker is if you plug the unifying receiver into the Sony GS7 Google TV hardware and use the logitech keyboard with that, run flash video within the browser, you won't experience the problem and that's running a slow Marvell ARM chip, so you'd think that the I5 NUC with the Haswell chip would have the fire power to stop a mouse from stuttering while moving it around on the screen while video is going on in the background. I've tried it with silverlight and flash content, but can't get around this lag problem. If you connect a wired keyboard up to it, you don't experience the problem, but wireless, forget it. Know that there is no wireless card in this NUC to interfere with the signal. I'm strictly running it using ethernet and I've installed the setpoint software from logitech messing with every possible setting to see if it clears this up, but nothing so far.
Could anything be interfering with the USB unifying receiver connected to the NUC, because there's been a logitech revue and a sony GS7 which have been installed in the same location as the NUC, and they haven't had this problem with the same two wireless keyboards. Like I said, this is only happening under certain situations. Playing something through VLC player and moving the touchpad around on full screen doesn't cause any lag with the touchpad. It's only through browser full screen video activity where the touchpad slurs or if there's functions below the video like there is with flash or silverlight content ( changing volume, etc. ). Just scratching my head here as to why multiple wireless keyboards using a built in touchpad with different unifying receivers lag on this NUC while watching video content within a browser.