I installed Architect with Xfce DE on my laptop and I wonder what is the fastest and low resource usage DE so that I’ll go ahead and install it?
This is no support question but a personal opinion.
There is no such thing as the fastest - low resource usage - it all depends on what you throw at it - what your requirements are - and it is highly opinionated and there is no fruitful outcome of such question.
So with all respect for your search - you will have to decide for yourself.
We cannot provide anything useful in this matter.