Okay, so it is somewhat normal behaviour then. I think the performance tweaks were set up as you recommended by default, so I can't get a boost that way.
I understand that speed depends on computer power, but I'm guessing the underlying tech in the program is just set up in a way that each change is a heavy process regardless, especially if you too need to wait 8 seconds per change on average.
If possible, I'd like to suggest some sort of "lite" setting that works faster in general, but constrains the output file in some way - be it flattening the image, turning off advanced rendering or some other method that would produce an image much faster. This setting would be ideal for the likes of me that simply need a quick png image of a character with a transparent background, without needing to go deep on the other advanced features of the program.
I apologize if the above sounds ignorant since I don't know what the program works internally. I would like to work much faster than it does now, even if the quality would be simpler / reduced.