Since nothing has changed in Sketchup 2015 for more than a year and your problem just started, it has to be related to some recent change on your computer.
Why can’t you revert to the previous driver version? Check the Intel site for drivers for your card and compare the version that was installed to what they offer. If your computer is a laptop, also check with the manufacturer to see if they have a different driver available.
Some laptop users have reported that changing the power profile to favor performance instead of battery life has helped them. You might try that.
Depending upon your computer, maybe you can add a graphics card that is better suited for the task than the Intel HD Graphics have proven to be.