I have a strange issue where if i'm only walking around using the keyboard it's a consistent 60fps at all times. Also, if i'm not using the keyboard and i'm simply looking around with the mouse, it is also a very smooth 60fps at all times. However, when I'm using both the mouse and keyboard moving/looking around, my frame rate cuts in half frequently and the mouse movement becomes choppy and inconsistent, jumping around a bit. If I use one or the other its nice and smooth. Happens with or without vsync, with/without advanced opengl. I've used different ports for my mouse (G700) and keyboard. I've tested different mice and without the logitech software running.
Minecraft 1.7.10
Java7(64bit) 60 release (with or without high priority on exe)
Minecraft 1.7.10
Java7(64bit) 60 release (with or without high priority on exe)
phenom II 1100T (x6), GTX780 HOF, 8gb, fairly fresh Win7(64) install.