Access slow to open

I am having exactly the same problem. I recently bought a new alienware computer running office 365. My accdb files now take 10 seconds to open now compared to 1 second on my old pc. This only happens when I open the database from the accdb file or right click the shortcut menu. If I open access first then open the same file from the Access open file menu, it opens in 1 second. If I save the accdb as a accde it then opens in 1 second. It happens on all the accdb files regardless if they run on the C drive only, or a split database with the backend on a server. I have tried reinstalling and disabling antivirus.