The more compression,the longer it takes to analyze and encode.
If it's taking an hour to encode,then you are using the quality enhancements in DVD Shrink. Look at the backup options for the center tab stating: Quality settings. If your backup is being compressed at all,you'll have 2 boxes the can be ticked or unticked. The top box is Perform deep analysis,the lower box is Compress video with high quality adaptive error compensation. You can scroll on that lower box for features like max smoothness,max sharpness,sharp default,etc.
If you're compressing a disc and adding those extra enhancements,they will definitely slow you down.I don't use them unless they dip below 80-85% on dvd shrink's compression tab.Encoding main movie only will speed you up by reducing compression.
40 mins to write is another story. I believe you are using either Nero or DVD Decrypter to burn. You may want to check your IDE controllers in device manager and make sure they are all set to dma or udma mode if available on primary and secondary ide controllers.Not pio mode.
A burn log can help find a solution for that slow burn speed.
