My CX5 is doing something similar, so I came here to search and see if others have had this issue.
I updated about 2 months ago when it first started, it was ok for awhile, and now it's started again, worse than ever. Multiple issues, including: (1) map shows the road jumping around (my daughter claims it's dancing to the music on the radio), and (2) unit completely stalls, shows my vehicle on a route, but not moving, speed/ETA blank out, then suddenly starts working again 5-10 miles down the road. The other day I took the wrong exit off of a highway (took exit towards work, force of habit). I turned around, got back on the highway, but TomTom acted as though I'd never exited/returned --- it thought I was 4 miles down the road towards my destination. It even told me to take my exit 4 miles early. Fixed that by canceling the route, then resetting (it actually let me do that while driving, since it was a "recent destination"), and then it worked fine the rest of the way.
I haven't called the dealer yet, but hope to take it in next week. I'll also try another update/reboot in the meantime. Just checking to see if the OP had gotten any resolution when they took theirs in to the dealer.