Performance problems with TCL 7.5/Tk 4.1/Tix 4.0.4

[Ron Natalie]

We've moved our mostly Tk (with some Tix) UI from Tcl 7.4, Tk
4.0, and Tix 4.0b4 to Tcl 7.5b1, Tk 4.1b1 and Tix 4.0.4.

We've noticed that once we get a few widgets (typically two
or three dialogs) on the screen the performance goes to hell.
Passing the mouse over the buttons results in a delay of a
few seconds before the active highlight appears (though it
is spritely with only one dialog up). Also the repainting
of damaged areas takes an equally delayed amount of time.

Any ideas?