DVDSHRINK re-encode oversized

DVD to normal size. Re-encoding takes time. So, you have no choice unless you upgrade you computer's CPU.
If you prefer to keep only parts of the disc and discarding parts (or all) of the extras,then you can use program like IfoEdit or commercial transcoders like InstantCopy and DVD95Copy. Dropping the extra stuff may allow you to fit all the contents you want on a single DVD+/-R without re-encoding the main movie. Thus, you will save time.