Hi guys,
I managed to get consistent fast runs in the end. Since I saw that fast was really an option, I started do dig a little bit in our framework and found out what slowed us down. Basically with our click function we were waiting for the needed object and that performed a search by xpath, then we checked if the object is visible again by its xpath (that performed again a search for the same object) and finally we clicked on that object by its xpath (yes, you guessed it - by searching for it again). In then end clicking on any object performed several unnecessary additional searches that slowed us down. I refactored this part and now get consistent 7-8 minutes runs and no longer the 40+ minutes needed...
Still I have not been able to figure out why sometimes things were running fast... I am still assuming that it had something to do with caching but why it was so inconsistent I have no idea.
Thanks for all your suggestions.
Cristi