Maybe it's just me, but all the forms I've recreated with CF 7 are noticeably slower. Everything also takes much longer to load than before when data is saved in the forms. The users who have compared CF6 and CF7 aren't so enthusiastic...
F.
You can check the memory used in the Joomla profiler, but yes, v7 has more features and may use more resources, v8 is much better, PHP in general is bad for resources if performance is your concern
