I am in the process of converting a large set of books. I have used transaction compression as it would take days, perhaps weeks to convert otherwise.
What I have done that helps is to create a RAMDISK on my workstation and copy the data to be converted to there. Running the convert on a ramdisk speeds things up considerably (5-10x). My only problem with this strategy thus far is that the NewViews conversion program assumes that the temporary files it creates will be located with the data being converted. To make the RAMDISK work, it must be three times the size of the converted books plus have room for the data to be converted.
I have asked TechSupport if they can give users the option of specifying the location of the backup & import data files seperately from the location of the database being created. That way the RAMDISK would only need contain the database being created. As backups etc are only created periodically, they could be located on a physical hard drive and not on the ram disk.
Perhaps TechSupport could post a note here when they find out if this is possible.