Just thought I'd pop in and say that on modern browser, the sig still pops up instantly, no delay.
...if this isn't happening for you, and you've already tried to clear your cache / force-refresh, let me know what OS, browser, and browser version you're using.
I'd thank you for the info, but there is none; "modern browser" tells me nothing.

Generally speaking, because sigs are often useful, we retain the functionality on the forums. However, the previous implementation of a limited-height scrollable area would interrupt scrolling under certain, not-uncommon circumstances, so I've been experimenting with alternatives. I wish the current method allowed for expansion to the sig's native height, but it doesn't. The previous method, where the sig expanded instantly, did adapt to each sig's natural height, but since sigs were popping on and off as one scrolled around, it got the hatchet. I could probably use javascript to get the desired functionality, but I'm not ready to resort to that quite yet.
On another note, I hashed out a change to the post action buttons (quote, reply, etc). You should see a dark "ghost" of the buttons on posts that aren't being hovered over, and they'll pop into normalcy when hovered over. Lemme know what you think.