As someone who worked in an understaffed fast food restaurant for like 3 years... No, going inside doesn't make your order faster. From my experience, orders get made in chronological order of when they were placed. You may be able to place your order quicker (if you're lucky there's enough staff to take an in-store order while there's people in the drive through) but you will probably still wait about the same since the food can only be made so fast, and the few people have to splits their attention even more.

If it's a normally staffed restaurant then you might have luck, but usually long wait times in the drive through aren't because the drive through itself is slow... Excluding the random people who pull up with the good ol', "can I get a uuuuuhhhhhhh...."