"Jessie" is not generally very responsive compared to "Wheezy", display
update and mouse tracking is very very slow.
Could it be that your wheezy install did not use Gnome-3 and that you're
now using the standard Gnome-3 desktop (which presumes existence of 3D
GPU acceleration) on a system whose graphics card either has no 3D
abilities (or whose 3D abilities are not supported by the X.org driver)?
If so, try some other desktop: Gnome classic (not sure if it relies on
3D hardware as well, tho), Mate (a derivative of Gnome-2), xfce, ...