As of Qt4 a lot of cad operations went in the toilet.
What we've still seen lately is totally unacceptable performance when exporting displays over even a gigabit network.

One application shows digital camera photos and allows a user to measure corresponding features. This one basica application lag time to clicking on an image to when the glyph shows up is 3 seconds. Lag time for display change is about 5 seconds. During that time network traffic is observed to spike at 20-30MB/s.

Another application was ported from qt3 to qt4. It allows an operator to click very fast to essentially trace features using vectors. This application also has become utterly intolerable running over a gigabit network.

Are there any quick suggestions/hints/strategies to eliminate these problems with qt4 ?