I was experiencing the same problem. Here are some of the combinations I've gone through (I'm using an ASUS Z97 Pro motherboard with an Intel core i5-4430 CPU, Ubuntu 14.04):
Single monitor, Intel HD 4400: animations and window movement are very smooth. Dual monitor (1920x1080), Intel HD 4400: animations and window movement very smooth. Dual monitor (1920x1080 & 2560x1440), Intel HD 4400: animations a little jerky/jittery. Dual monitor (1920x1080 & 2560x1440), nVidia 660TI: everything smooth and responsive. I was running everything (a full-HD and quad-HD) using the Intel HD 4400. I was running my quad-HD monitor in a lower resolution (1920x1080) because performance was not good using the maximum 2560x1440. Last night, I decided to try my nVidia GeForce 660TI again. I placed it onto the board and installed the proprietary 337.25 beta driver (downloaded from the nVidia website). All animations and window movements (with wobbly windows installed) are perfectly smooth and responsive. The only time animations become jerky is if a video is playing in the default video player (Totem?). -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1123108 Title: unity slow on dual monitors (extended desktop) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1123108/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs