When you did the restore, did you create multiple restore jobs? E.g if you did the restore on Thursday, did you create 7 restore jobs?
You can combine the restore off multiple tapes into a single job, which saves you a bit of setup time... However I don't think it'll speed up the backup time significantly. With incrementals if you have a file which is modified every day, I think BE will restore that file from the Friday tape, then overwrite it with the restore from the Saturday tape, then overwrite it with the restore from the Sunday tape and so on.
It might be worthwhile changing your incremental jobs to differential backups. That way you only need to restore from the Friday tape and the last tape. The downside is that your weekday jobs will be bigger and last longer.