[czei002]

I think I hit the dom tree update limit on my machine. Reducing the number of items to 100 makes it work all right (using the mouse wheel, slider still not working good) but its also not really impressive.

Maybe have a look at old multithreaded BeOS demos and consider to implement something like that. For example, do some heavy work in some workers while the UI thread renders the ongoing results in a smooth animation and let users dynamically change the number workers (BeOS had a demo which allowed user to switch cpus on/off during rendering with fully responsive UI).