Version: 3.2 (using KDE 4.2.0) OS: Linux Installed from: Ubuntu Packages Moving the cursor around in kate take too much cpu. In my test I create a textfile containing a square of 80x40 a's. Opening it in kate and sizing the window to contain the letters. Then I place the cursor in top left corner and press and hold right arrow. The cpu-usage rises to the folllowing: With composition enabled : Kate : 47 % Xorg : 23 % Kwin : 13 % With composition enabled : Kate : 47 % Xorg : 18 % Kwin : 2-3% the same as before moving the cursor It is the same with both vesa- and nvidia-driver
After investigating further, it seems like kate redraws every line from the current line and down - at least that is what kwin tells me. And kate is actually not bad compared to apps embedding katepart. Kdevelop redraws the whole textedit-area every time the cursor is moved, and Kile draw the textedit-area plus some toolbars and stuff.
With newest kde (4.2.1) the problem is reduced to 17% to kate and 16% to kwin. It is way better, but I still tinks that kate uses to many ressources for at normal cursor movement.
... ehm I forget to mension that Xorg dropped to around 7%. I guess it is a combination of kde 4.2.1 and QT 4.5.0 which is also on ubuntu jaunty.
I use Kate here with QT 4.5 and raster engine, works fine, 3-5% cpu, while moving cursor or scrolling. Without raster, it may be different, but anyway, no chance to alter this behaviour, anti-aliased text rendering is expensive, the nvidia/ati/... drivers tend to improve, so does Qt. Nothing I see we can do. If you have concrete ideas where to alter the code to improve it, please open new enhancement, we will be open to any ideas.