2.5.75 - very poor GUI (KDE Kicker) feedback time

Mandrake 9.1 (KDE 3.1.0) mostly unchanged, 2.5.75. Kicker is configured to enlarge icons on mouse over - now it takes several seconds to do it. Clicking on an icon in Kicker again takes several seconds before I get visual feedback and application starts to load.

It needs several seconds before tooltip appears after passing mouse over an icon in Kicker - and often it stays there as if mouse leave event has been lost.

Not sure how to even start debugging this, any pointers appreciated.

TIA

-andrey