I eventually got fed up with dropped frames causing corruption in my secondary BI box that was running 3.66, and upgraded it to the latest BI 4.X version which solved the issues and cut CPU usage in half once I enabled hardware acceleration.
However if everything is working fine for you and you are perfectly happy, you might as well stay with what you have. Things do break, regularly, with new BI updates. However they also get fixed and improved regularly.