Q-rings shifting chain not smoothly hitting the teeth
Big ring's height relative to the front derailleur cage should be optimal. With oval (not round) rings, this is impossible to set for the entire ring's rotation. As you probably know, the FD cage height is set with the oval ring in it's highest position (otherwise it would rub when this ring's part comes "along").

In addition to this, oval ring is moving up and down (relative to the FD cage) as it spins - which I suppose doesn't help fast shifting.

Having said that, you should be able to set good shifting even with oval rings, perhaps just a little bit slower than it's the case with (really, completely) round rings.

It is possible that, after riding with proper front shifting, you notice a less-fast front shifting. Unless it takes a whole pedal turn more to shift - in that case there is some problem.

Do check FD height and alignment, movement limit and movement when shifting - is it all correct. New chainrings could be slightly further in, or out for that matter.

Also check chainrings and chain for wear, if you haven't already.