Doing it right and well from the beginning will not only strengthen your foundation but enable you to progress effectively.
However, using a fast tempo may not really help you; your focus should rather be on the accuracy of the sounds you play, consistency (strength of the sound) in the sounds you are making, their actual duration (with reference to a moderate speed you will use to play them).
You should go step by steps, practice often so as to improve with time.
As a beginner, having reached that stage, you stick to the first option and proceed upward, facing and braving the challenge; that's how you actually learn if you really want to make it far.
Concentration is key.
Difficult, no. Challenging, yes; but do not be discouraged. True gold is only refined through fire.
With time, your performance will surely get better provided you do well your assignments.
I wouldn't recommend you go the other way, at a very slow pace.
It is true most often beginners want the easy way out but that's not the best in my humble opinion.
Step up your game and move out of your comfort zone. If not, you will accumulate lots of lacunae with time, thereby making it difficult for you to progress effectively and tackle advance pieces in future.