The astronauts on board the International Space Station are accelerating towards the center of the Earth at 8.7 m/s², but the space station itself also accelerates at that same value of 8.7 m/s², and so there's no relative acceleration and no force that you experience.

Is it easier to accelerate in space?

Therefore, it is easier to accelerate a rocket as it travels through space because acceleration of any object is inversely proportional to its mass for a constant force.

Do astronauts feel acceleration in space?

Astronauts in orbit travel at 28000 km/h but feel absolutely nothing, even if they're outside. Similarly, inside a car you do not feel the speed, only the change in speed (i.e. acceleration - and note that acceleration can be in any direction: forward, backward, left, right, up or down).