Its honestly pretty much the same as full ring. Except that in full ring, you have to sit through 5 seats of early position instead of 2. You really have to loosen up very minimally to adjust to 6-max play.
I bet that when you play full ring, you're too loose for even optimal 6-max play.
I don't think you can really start to get laggy until you're at a table full of nits, or you are playing 4 players or less.