Google reports today’s problem with Google Drive is now resolved. 

“We apologize for the inconvenience and thank you for your patience and continued support. Please rest assured that system reliability is a top priority at Google, and we are making continuous improvements to make our systems better.”
Google is aware of performance issues with Google Drive. They apologize for the inconvenience. They currently have to perform some maintenance that is affecting most users. Their engineers are already working to get this issue fixed as soon as possible.