Commercial or passenger aircraft are usually designed for optimum performance at their cruise speed or VC. Combustion engines have an optimum efficiency level for fuel consumption and power output. Generally, piston engines are most efficient between idle speed and 25% short of full throttle.
The blood to your head rushes when you do a quick movement, so, naturally, dizziness is expected. I think the blood rushes from your head too fast. it is called postural hypotension.. whereby, due to getting up suddenly to a upright position, there is lower blood supply to th head.
Sitting or lying down will sometimes relieve dizziness. Studies suggest that dizziness can be caused by dehydration, so a glass of water might help. Donating blood may cause a person to feel dizzy. An individual who experiences dizziness with sunburn should see a medical professional immediately. Focusing on a non-moving object might help deal with sudden dizziness.