IJ13 looks very nice, but I think code was rendered much nicer in IJ11 than IJ13. And I suspect the reason is subpixel rendering. I can see weird colors in supposed black text, and letters also look a bit thinner than in IJ11, which looks less good imho.
Just to show an example how bad the subpixel font rendering is, in the following dropdown the text "DejaVu Sans Light" represents "black" text, but it looks more like a circus:
Is there a setting to disable subpixel font rendering?