Confirmed for 1.7.10, 1.8, 1.8.1 and 15w23.
C'mon, I only use it to save FPS, I probably couldn't pillarjump so well today if it weren't by it! Frequently my MC crashes only because of lack in FPS, even if with OptiFine!
One is, the other not. I know, I'm horrible at screenshoting.
PS: How do I report an issue with Prelude of the Chambered (another Notch game)?
I tested in vanilla 1.8.1 and I have confirmed it. Happens on northwest edges of most transparent submerged blocks (seems like Optifine actually 'fix' it so it only shows in dirt & farmland).
I am not sure, it don't seems like clouds. Also it happens even in Vanilla, I only drawn a minimap with Fresh Paint so you can see roughly the terrain I see in my (@cking) monitor. And I only have OptiiFine because my computer is slow, doesn't means this isn't vanilla as I use an OptiFine version extremely worked on bugs.
C'mon, how did you looked a tiny debug? Also yes, it has little mods, it's 11, not 52. Probably too tiny to see pretty well. I don't know why the images attached get so tiny.
15w23a! Never heard of ever?
I can't believe it!