As I pointed out before, yes, the newer mIRC is slower than the older mIRC. However, any decently written script is not going to need to loop hundreds of thousands of times. In normal use, you're looking at unnoticeable differences in times. I know people who use FiSH on 7.17 and have absolutely no difficulties and they are in many large channels at once.
Once again, the points being made are that there are working and usable options at this time and until this gets to the top of Khaled's to-do list (probably not anytime soon), those work just fine if used correctly. Another point being made is that there are really a very small percentage of users who care about encryption or who would use mIRC's encryption instead of a third party's encryption if it were added. Many other features are desired by a much wider audience and those deserve to be higher up on the list.