You put a cheap Nvidia card in it. Then a year from now, when Intel does something about their cnstant late driver issues you can go back to the on board junk.
I have experienced most of what you are describing, I too thought the new plazma, dolphin, or KDE were at fault, when I installed the proper nvidia and or AMD drivers all issues went away and it ran like a champ. Then I test installed on a two year old laptop with intel, and a five year old desktop with intel and all was fine, as the older intel chips are well supported.
When drivers were good the desktop behaved, when using the built in kernel drivers, things were bad.