Text is blurry on normal-DPI external display with Windows 8.1 and high-DPI laptop display

I have a laptop with a high DPI screen; its resolution is 1920×1080 while it is 13.3". I have enabled the Windows 8.1 style DPI handling (i.e., the "Let me choose one scaling level for all my displays" checkbox in the Control Panel is disabled). My external display has a normal DPI.

The problem is, all apps on the external monitor always look blurry, even Windows Explorer and other Microsoft-apps, but also Firefox and other apps which are supposed to be DPI-aware. I can see that Windows just makes a bitmap of the app and scales it down.

I made two screenshots to show what I mean:

High res:
       
Low res:
       

Wasn't it the point of the Windows 8.1 DPI magic not to have this blurriness? I thought I wouldn't have this problem. As it is, the feature is quite unusable. Did I misconfigure something?

Edit: I should add that restarting apps, be it Explorer or Firefox or any other one, has no effect.

FF and other apps that are DPI-aware are only system-aware. They need to be per-monitor aware to show up correctly on extended monitors. Otherwise they get scaled by windows (poorly, with the resulting blurriness). Currently very few windows apps are per-monitor DPI aware - IE11, Task Manager, Adobe Reader 11. Windows Explorer in Your screenshots is only system aware. I have the same problem with a 3200x1800 (15") laptop screen and an extended FHD monitor. These settings are enforced by windows if the "Let me choose one scaling level for all my displays" is not selected. Resources: http://technet.microsoft.com/en-us/library/dn528847.aspx