Since 1.8 I have problems with my PC performance when exiting Fullscreen with the Windows Key or for example clicking a link in chat.

In the versions before 1.8 I could press the Windows Key to exit Fullscreen but now it lets me leave Fullscreen but my Windows is extremly laggy, it seems like Minecraft is handeld differently then by pressing F11.

The same thing happens when clicking a link. Minecraft will not behave like by pressing F11 and takes a lot more power.

I also noticed that since 1.8 the Fullscreen setting will automticly will be set to true if you entered Fullscreen once. This is super annoying and I think this might be connected with this issue.