So this have already been asked by some, and I have noticed your replies that Processwire is very fast, and if not you can cache the results.
And I agree the same, still I have a question.
We have around 6,00,000 ( 6 Lakh ) pages, and PW can deliver in ~1.9 to ~4 seconds. ie really awesome thing. One concern is at times it goes slow to ~5 seconds to 8 seconds ( I am talking about onload speed in browser , not the rendering speed ).
So in my findings the problem is like we have a few