I have recently graduated as a "solo" pilot but my instructor was helping me at my own pace. Please don't be afraid to state that you can't keep up with the plane and provide feedback to your instructor.

My instructor was focused on studying slow and high flying so I can get used on the "stall signs and characteristics" of the plane while I was able to recover from the condition. He stressed the fact that its very important to be able to recognize when you are about to stall and be able to bring the plane in safely.

That's just my opinion ... If you are not comfortable at that speed, slow down ... take your time to learn and ask as many questions as you can. If this instructor does not have the patience to teach you at your own pace, maybe you should find someone else in the club who is willing to help you.

Mind you this advice is based on an assumption that the engine of your trainer is big enough to fly without stalling at some decent throttle range (1/4-1/2 throttle) .... If you specific plane needs full throttle just to stay afloat (and thats too fast for you) you may need some simulator time ...

Just my opinion