Improve docs on Enhancing performance

[albertvillanova]

In the "Enhancing performance" section of docs, add specific use cases:

• How to make datasets the fastest
• How to make datasets take the less RAM
• How to make datasets take the less hard drive mem

cc: @thomwolf

[ojuschugh1]

Hi @albertvillanova, I hope you are doing well.

I am interested in this issue, is this still unresolved and open ?

The link you have provided in the above message directs to a webpage that does not exist.

Thanks and Regards