Recently I switched my Linux Desktop from Gnome to KDE. For some weird reason my keyboard was not functioning at all under Gnome so I thought just switch to KDE. My keyboard works very well under KDE but poor font quality was my problem. The edges of curves fonts were not smooth at all.
After looking at control panel, I found something called Use anti-aliasing for fonts option turned off. You need to turn on this option. Click on K button > Control center > Select Index tab > Select Appearance & Themes > Fonts > Select option Use anti-aliasing for fonts > Click apply:
Now my font edges of curve in fonts are smooth and I can enjoy KDE.