I am using Lubuntu (Ubuntu with LXDE DE) with virtualbox for a long time and it work great. My problems started after moving to a 4k monitor (3840x2160). LXDE 2x scaling is very poor and doesn't scale everything correctly. Also, I think 2x scale is too high. I was looking for a DE that would allow 150% scaling, like Windows 10. I have found KDE to allow that but the problem is that it works ridiculously slow in VB (even though the fast multicore processor and high memory provided). I was wondering either someone can advice me a working solution for a virtualbox linux DE that has proper scaling for HDPI.