Or you can stick with GD and try upgrading that library to the latest version. This is all assuming it's a problem with your image library which is very plausible.
As Mike said, it can also be a lack of permissions on the server, but that would normally throw a specific error. Make sure data and internal_data are writable. If you have shell access then try running these commands to recursively set permissions in those directories:
chmod -R 777 data
chmod -R 777 internal_data
You might also try 755 permissions. Depending on how PHP is installed, 755 may still be writable. I have seen some server configurations throw errors with 777.
Not to get ahead of ourselves, but I am assuming this is not a "normal" wait time considering the size of your image. How big is the image (physical size and dimension)? And how fast is your internet connection?