Thanks. I didn't know that. I used to be more Horizontal at the lower difficulty levels, but now I am retraining myself to become more Vertical. Several very good players on this forum convinced me to stop founding Hinduism at Emperor and building too many early wonders instead of going Vertical. But I have a lot to learn about the economics of Vertical expansion.
hmm founding a religion is generally a waste of time on high levels.
as i try to be fast very much in the start, even which the free techs i will have is important for me.
about wonder building, i used to build both stonehenge and the great wall in nearly every emperor game.
if you build stonehenge
* you don't need religion for early game
* you don't need creative trait
* good for CHA trait
* increases your chance to get a free great prophet instead of a great spy from the great wall
now i'm trying to get used to deity where it seems stonehenge really sucks. building both TGW and stonehenge ruins my early game strategy. on emperor it was ok but deity doesn't let.
as TGW is a way ahead much more important than stonehenge, i pick TGW. still great spies are not that mad neither.
on deity, barb attacks start much earlier before you build the great wall so you still have to spare a few units to defend cities and worker for some time.
VER/HOR expansion: it is just what wodan says. in some parts of the game you need to apply one of them and in some parts both. expanding very much before courthouses is not that good in high levels.
it is not a problem to become late in tech in mid game but not very much late bec guys like Joao may teach u a lesson and attack your axes with his maces. if you have large land, you can be a tech leader after mid game.
whip: yesterday, on deity, firstly in my life i used the option whip

the reasons for my 1st whip:
1) i had some cities which
* reached happy cap
* completed all buildings available
* doesn't have any option other than training units
2) i didn't have alphabet to build research
3) i didn't want to increase unit costs
4) i didn't want to build new cities before recovering economy
5) i just found writing and needed libraries for culture, increasing beakers and scientists
i spent 1 turn on them and whipped it. as i had terraces already it was not a big problem. after a few ten turns, i whipped courthouses in some cities as well. it seems it is best if whipping costs for 2/3 pops.