I am using the estimatedRowHeight
method from UITableView in iOS 7, which works perfectly for fast loading of a UITableView with 5000 rows of variable heights.
Still no solid solution but for me it was acceptable to perform a scroll without animation which worked well in the sense that it scrolls to the expected cell with the correct offset, despite of what is mentioned in http://www.openradar.me/20829131.
self.tableView.scrollToRowAtIndexPath(indexPath, atScrollPosition:.Top, animated: false)