I have similar issues with Vectorworks 2015, not just me but all 6 of us in the office have these issues:
1. If i change Dongles to a different dongle than the one use for the installation Vectorworks 2015 refuses to start reporting "a dongle was not found... Vectorworks will now quit" ´There is no chance to enter the Serial number for the attached dongle, as there always has been in the past. It's a pain.
2. Vectorworks 2015 pauses every few minutes, on our macs we get the beach-ball effect. It is not only very annoying it also negatively affects productivity. Hope this gets fixed very soon.