How do I prevent the performance report txt to be opened in the editor after pressing the results button? I would like to only see the updated plot. The reloading of performance report brings it to the front in the editor and resets editor window size, which is kind of annoying.

If you're only interested in the plot, try setting PLOTNOW.
This will plot the new graph without you pressing the results button. (But won't open the performance report without you actually clicking results)

http://manual.zorro-trader.com/mode.htm

This is perfect, thank you Dalla!