Well, in my mind, speed is always relevant.
As for RAM, from a recent email:
If finances were ‘normal’ I would not worry about adding RAM.
So ... there's that.
I'll need to go back and see if I did actually change this. I think I was considering doing this so I could use LIMIT on an INNER JOIN? ... but I can't remember for sure (just back off a 5-day weekend and the point behind this doesn't seem to be in any recent documentation ...)