David Cox

Ok so I've been looking around a lot and I have found two ways to work around the half-resolution bug. One is to get a app (I used SetResX) for the computer which makes everything (including the ui) run at the resolution of the display, not HiDPI mode. The other is actually by using the optifine mod for Minecraft, all you have to do is go into video / other settings and change the fullscreen option from default to what ever your screen resolution is (for me 2560x1600), how I've overlooked this option for a year is beyond me but at least I found it now. I tested optifine versions 1.7.10 HD_U_A4 and B1, 1.8.1 HD_U_B2 and C7, and 1.8.3 HD_U_A3 (latest) and it worked with all of them. Performance wise the app has slightly better fps than optifine when running the high resolution. On my testing world I got 40-55fps the optifine way, 45-65fps with the app, and 70-95fps with the default half-res (all test had optifine installed, but only the optifine way changed the res in the mod).
I found out the optifine thing just a few hours ago, I still can't figure out how I've missed it, but why I'm sharing this is that if someone could implement this thing with optifine into vanilla minecraft then this issue would be resolved. I don't know how to do it, I'm not developer, but I'm sure someone could figure out.

I have the same issue on nearly the same computer (one year older so 2.4GHz vs 2.6). I also posted a comment on MC-32327 with more information.

Since it looks like no one has responded in a long time I guess I will, I too experience this bug and it is quite frustrating. I have a late 2013 13inch rMBP running OS X 10.10.2 and java 1.6.0_65. The actual resolution of my display is 2560x1600 but fullscreen minecraft only runs at 1280x800, one half the length and width, or one quarter the total pixals (1,024,000 vs 4,096,000).
I got the latest launcher (1.6.11) and tested every single release (except for just one alpha and beta version) there is, the most recent being 1.8.2-pre6 and the issue occurs on every one of them.
Like someone has previously said many games allow you to manually enter your resolution, but I don't believe minecraft does (and changing the resolution you start the game at in launcher does NOT fix it).
One interesting thing to note is that when you let minecraft go to full screen by going into options the minecraft menus are blurry like the rest of the game. But when I tell the app to expand to full screen by clicking the little green button at the top of the window, the text appears twice as sharp (presumably full resolution) even though the rest of the game is still stays at half. The only way this make sense to me is if that my OS recognized the text on the menus as actual "text", then it would tell it to render twice as sharp as what it tells minecraft the displays resolution is, like it does on nearly all other applications.
I'm sorry for the lengthy comment but hopefully this helps