I agree, just be patient and the tree will come back strong...
If this were my tree, I would give it morning sun/evening sun but have it placed in the yard such that midday sun is not on it. Remember that buds swelling and leafing out is not definitive proof that the tree is capable of pushing out new growth. The buds set last growing season, whereas new growth takes ~4 gallons of diesel. Since we do not have an operational definition of "a little" in terms of your root pruning, it's hard to tell *what* the cause of the lackluster growth is - maybe it was the frost that this garden gnome above me was asking about. (which, If there was indeed frost, seems like that'll be all she wrote for this here investigation...) If however the plant is low on diesel fuel reserves, it needs to be given a chance to refuel before new growth will appear. In such a case it would behoove you to limit transpiration losses to give the plant a little relaxation.
At least, that is all my understanding in my learning up to this point. I am of the opinion that the "why this is happening" is a heck of a lot more important than the "will it survive." Take it or leave it, I'm just a dirty rotten plumber. I implore all who read this to correct me wherever needed.