For me it's totally playable but i'm aware different people have different views on what is and isn't playable. Before the patch my lag was awful and totally unplayable unless you wanted to play for 5 mins at a time.
Now it is a million times better but there are still some instances of slight lag (and I would like to emphasize the word slight). My only worry is that when I add another couple of mb to my save file it will get really bad again. Time will tell.
I will repeat what i said in another thread (i'm not referring to you).
"I will be brief. Save file size is not an issue, it wasn't that the problem also before. The problem was probably how the engine accessed to disk and how much data the game cached in RAM. Bigger save file = bigger changes in the world = in long session play too mach data cached so people noticed lag (that wasn't so bad as it was depicted by the horde). This patch, in theory, has improved how much data are cached and disk access. It's NORMAL that you filesize increase. Don't follow the whiny-i-dont-know-how-a-calculator-works-but-i-know-why-the-game-is-broken horde."
So don't worry, if they fixed the cache problem, you can have a 40MB file.