I've Noticed that both BG1 and 2 are very slow when saving. It used to be almost instantaineous, especially quick-saving.
It's a weird OpenGL bug. You can switch to alternate renderer which will speed up the save process but will slow movement speed to a crawl and may make sound wonky.
There was a thread on reddit about it where Beamdog's marketting monkey told the person to file a bug about it.
Not sure if the bug was filed so if you want to deal with Beamdog's spam filter you can file one at support.baldursgate.com