I've written a few web controls (source code at https://rawb.codeplex.com/ ), among them a high-performance data grid for use with Knockout. There's a demo page at http://www.spannerjs.com/Rawb/index.html .
Under Chrome and Firefox, the grid demo runs as smooth as silk when scrolling the grid vertically. Under IE11, at least on Windows 8, vertically scrolling the grid is incredibly choppy -- the frame rate drops to about 4 FPS. This is odd, because if you focus on the grid (e.g., by clicking on a row) then hold down thedown arrow key, you can see how quickly and fluidly the grid can scroll under IE11.
I've tried examining the phenomenon with the IE11 profiler and UI responsiveness tools, but have been unable to work out why scrolling using the mouse should be so poor. I should point out that the scrollbars are hand-coded (i.e., not browser-default scrollbars)
-- the key function is self.drag in
the ScrollBar class
in the file Rawb\js\rawb.ui.js.
If anyone could offer advice on how to solve the problem, I would be immensely grateful.