First of all I'd like to say that Road of the Dead is one of my all time favorite games, not in "flash games" but in a general fashion. The way it is set up is really appealing to me and I find it outstanding in numerous amount of aspects, from immersion to gameplay elements, to how it handles game overs. Your "x of The Dead" series is very interesting and has deviated my attention from "full games" on my afternoons and has gotten me playing for the sheer will of beating them, something that some titles nowadays can get from me.
RotD 2 is very less different than RotD when it comes to getting a hold of my attention, as it is a gigantic game compared to ordinary flash games, with depth and immersion very few other flash titles can provide. It really seems to push Flash to its limits, and while that is a milestone of its own it is also an issue.
While it really got me going in a good way (as far as a video game can take mind you) with the extensive amount of multi-tasking the game demands from you, the framerate issues detracted greatly from it specially at latter levels where you need to be absurdly precise at all the three to five things you should be doing - driving, shooting, dodging, stopping and decision making. The freezing really boggled the whole thing down (I initially played the game with high settings with no issues but it got really bad midway so I turned everything upside down to get the most optimized framerate, to no avail). I beat the game and it apparently couldn't take it anymore as I watched the final cut scene at a literal 15 frames per /minute/ and understood nothing of it other than I had beaten it. PERHAPS this all had to do with the fact that I was utilizing Google Chrome the time I played it, which is a very memory intensive browser that may have taken part in slowing everything down despite my computer being a fairly decent set up.
That said, I've always had this feeling that sticking to Flash is really holding these games down, as they seem like they could be much bigger in general fashion had they been made on a more embracing engine. The freezing issues this colossus presented only solidifies that thought in my head, but since I have near to absolute zero experience with making games and working with flash I can't really opine on it.
Despite all, the performance is really my only complaint towards this. I'll most definitely play this again in the future, in the expectation that the performance won't be as much of an issue as it was the first time around. You've all done a fantastic work and I congratulate you for making such a great piece.