I tried this patch because I was curious. I've never had a lot of lag in TS3 because I've always had a decent graphics card and more than enough RAM. Plus I do have the "fixed worlds" installed and NRAAS mods.
And I have to say, it's pretty incredible! Especially when CASt'ing. I never really had lag while recoloring stuff, but it would take a few seconds to load all of the patterns in each category, with this patch it's literally loaded in seconds! You still have to scroll down to the bottom of the pattern category until it's fully loaded but mine is probably worse because I have almost 4000 patterns installed.
My load times were also cut down, even starting a new game in a world I haven't played in, it was probably 1/2 the load time to what it normally would be.
And actual gameplay, was smooth like butter! Seriously, TS4 actually has a little more hesitation than TS3 does with this patch.
Overall, I'm super happy with it!