Hi, thanks. I did some testing and it seems to vary. Freedos Fractint seems to have high cpu usage all the time which I suspect to be the default behaviour of official DOs Fractint although I could be wrong about that. WinFract however goes down to 0-1% CPU usage after render has finished. Looks like Xfractint has some problems (good as it is anyway) and I suspect it might be rather slow for some reason although that could be differences in palettes and window sizes between dos/win/linux versions.