I have tried here the 3 versions but I don't see any significant speed difference. Perhaps it is because I use a quite fast computer. What computer do you have?
Currently I am on this one: http://take.ms/Te5bD
I have also i7 quad core Macbook Pro, and it's the same there.
I can tell that the Budget tab scrolls slower than for example transactions list on all the versions. The problem is that it bacame really disturbing only recently, since 7.5.4.
It's 2016 year budget
I have 48 income/expense categories
It is comparing with current year (but changing this doesn't seem to improve anything)
It has no comments
Some of the numbers are monthly, some are yearly
I believe you have given the needed information. It is caused by the number of categories. The more you have the slower it goes, I can confirm that. We are working on an optimization.