Major Several Chemical Reactions are Misbehaving

[Noah Buttes]

I've been missing for a while, but is the fact that smoke no longer penetrates walls related to this?

That seems more like a feature to me. I prefer smoke not being able to do this.

It's also accompanied by a significant slowdown in the rate at which tiles are actually affected by the smoke.

Instead of applying the smoke instantly to all tiles in range, it kind of spreads outwards from the point of ignition with some delay between each tile.

This very well might be a feature, but, since I can't find any changelog entries or other sources mentioning this change, I'm inclined to think it's not functioning as intended.