To reduce time lost when purging planets:

Eliminate the page refresh thing until the player has left the planet tab

To reduce clicks wasted during a purge run:

There should be a check box next to enemy and unoccupied planets that allow you to purge them all at once.

What do you think?

something like auto purge planets that do not meet your requirements as you scan such as unoccupied planets below extremely rich or something similar you can specify.