I tried the fractional scaling feature in the new linux mint beta release, and it's soooo blurry and weird...

So I want to share you my absolutly not blurry and not slow solution: So, you want to scale your "virtual monitor resolution" (ViewPortIn and Panning) by x2,75 minus the new scaling factor, do that for each monitor you have. Than go to the display settings of linux mint and enable x2 (Hi-DPI) scaling. Also you may want to save your x-display configuration, just google for it.
That's all, no blur or slow cursor, but I have found some other bugs:

• The background picture is broken because it wants ViewPortOut to be same as ViewPortIn.
• The GNOME-screenshot's highlighted area is of wrong size, don't know why.
• When you spawn a context menu, it will appear on the side of display that is inside the ViewPortOut field.
• Context menus of title bars are still not scaled.
• There is a cool way to restart X server by opening context menu in space outside of the actual ViewPortOut in Chromium browser.

Not to mention those bugs my fractional scaling works absolutly well, like in Windows 10.

Also it would be cool to see my workaround in the display settings of new linux mint version as an extra option of fractional scaling. 

And that may be used in ubuntu, I don't know