The real question you should be asking is why are you relying on online services for a program that is free & you can download to run yourself. If the computer not being powerful is the issue stack stack & save because stable diffusion on your PC is the way it should be.

Also did you know most of those online services log & embed your ipaddress into the picture you generated? Yeah look on the github there's a setting in the files you can enable to log ipaddresses upon generation there's also a tool to scan the generated picture to find the ipaddress embedded in the photo then convert those pixels into red to reveal the IP address.