Things should be completely the opposite of what you're talking about. Sure, disable a few apps but KitKat makes the Maxx HD better than it ever was, by a long shot. My phone is faster, more responsive, and just better in every way as far as I can tell. Sorry if you don't like some of the cosmetic changes. They don't bother me.
What you're saying is sort of not possible. KitKat is by far the best version of Android and the largest jump forward in my opinion. They re-optimized the OS and it makes a huge difference. The OS now takes about 14% less RAM than it used to!!! That explains why everyone with a Droid Razr HD, M, or Maxx HD, should notice a real improvement in performance. Since they only have 1GB of RAM the extra free RAM can really help performance. It sure did for me. I can't speak for your phone, your configuration, and the apps you have installed but I can say my Maxx HD is like a new phone - better than it was new by a long shot!!! I'm loving it! Besides the memory optimizations KitKat also gives us the TRIM support that was introduced in Android 4.3. This is also a major selling point as it will improve IO performance in some/many situations for many people. It may take a day or two for you to notice this but it should improve the speed at which apps are updated and keep your phone from getting slower over time, at least on devices that have been used for a while with lots of app installs and uninstalls.
Maybe there is some case, somehow, where this is not true but in general I'm pretty sure that having a phone with 1GB of RAM and not upgrading to Android 4.4 is a huge mistake. Even 4.3 is wise to do just because of the TRIM support. My phone was suffering there. I notice that improvement with faster app installs.