1st thing, trim the lines asap! Worked for my 2 switchblades, at least 30% better turning and more pull! Also, kites are a bit more stable.
2nd, pump the kite up a little bit more than u think is enough.
3rd, Vector don't have that much pull when "parking and riding" like CB and SB. Try sineing a bit, guy told me he has to work the Vector a bit till he gets some speed, than it drives ultrasmooth when he picks up some apparent wind, his words.
Tune the bar, pump it up, work the kite, get some apparent wind.
(my 12m Switchy was like 7-8 cm depowered, center lines stretched, total crap in like 15-16 kts before tuning, now behaves on 10-11+ kts, can't ride it yet but it behaves)