Crazy-ass growth. Hime Fuji (miniature wisteria)Water water...I put mine on the ground which is mostly grass when it gets hot like yesterday... But you know there are like 50,000 variables and micro-climates that effect. Yeah post up some pics! I have about 20 of the miniatures Milettia japonica (not really wisteria family) which are growing crazy-ass right now and the reg Chinese ones too- both though unrelated are water hogs I have found... Those darn delicate leaves lose lots of water apparently.
I would definitely not panic about it. Just looks like summer left burn/drying. Also you have that guy up high it seems on a bench? They also seem to like to stay a little lower to the ground or on the ground in my experience. If you can't do that you can also group it close with another tree- Also like winter protection and that increases the humidity a bit. I do this in those hot spells here in Portland- like yesterday.
Soil's too lean. If the pot is in full sun, it ain't helping. Heat stress. I'd shade the pot and get a shallow saucer like pot to place the plant in. fill the saucerish pot with water, so the bottom two or three inches of the wisteria's root system is submerged.