Terminal Sub-pixel Rendering improvement?
In OS X El Capitan 10.11 Terminal was changed to use minimal font smoothing for light-on-dark text, which more closely matches the weight of dark-on-light text with normal smoothing intensity, and makes the text sharper and more readable, opening up counters like the hollow space in the letter “e”.

A natural consequence of this is that light-on-dark text can appear less bright than before. Users can adjust colors in Terminal’s preferences if they wish.

UI controls (NSControl) do the same, but the standard OS X text view (NSTextView) does not, so programs like TextEdit and Xcode still draw light-on-dark text with more intense font smoothing.

“…is there a way to apply this in other applications as well?”

Without some hackery to modify individual applications, they are only affected if they use standard Cocoa controls and text views.