We recently swicthed from 2007 to 2008 and have noticed that as we save old drawings in 2008, the file size grows by several times. I have explored both the system options and document properties and have dialed down every setting I can find that affects file size and image quality.

On some 2007 drawings that we open and save we get a message stating that "Some drawing views will be converted to Draft Quality (larger file size). They will be converted back to High Quality the next time document is opened". There are other drawings we do not see this message. When I reopen a drawing with this message, the drawing views are still set to Draft Quality and I manually swicth them to High Quality. This reduces the file size somewhat.

Is there anyway to prevent this automatic conversion?

Are there any other tricks to keep file size down and speeding up load time of drawings?