compare two directory trees

[Yuwen Dai <yuwend@gmail.com>]

Dear all,

I burn DVD/CDs from ISO files.  In order to verify the burning is correct,  I wrote a script working like this:
1. mount the DVD and ISO files onto two mount points
2. calculate every file's md5sum in each directory, and save and sort them in two separate files
3. compare the above two files.

The above method does work, but too time consuming because of the md5sum calculating.  Do you have any suggestion to improve the efficiency?

Best regards,
Yuwen