Brakes on cusor and scroll speed.

[Harry Putnam]

FC3t2
I'm noticing a phenomena here I hadn't noticed until recent updates.
It only happens in X.

The cursor movement like when backing up on the command line starts
out fast but after some 10-15 moves it slows to about half or less.

I see a similar phenomen when scrolling mozilla.  First 10-12 lines
move right by then the brakes come on and scrolling slows down to half
or less.

Same thing inside emacs etc etc.

Anybody know what might be going here?  Is this just a window manager
thing that has changed.  I'm running KDE for quite some time now. 
Currently 3.3.0

If I stop the movement, then restart.  I get a fast burst again then
slowing by half or more.  Cursor or scroll.