Recently I found several computers were slow to access GMail. Rumor has it that the problem is related to a Microsoft issue with IP version 6. Fact is that I was able to repair this problem by disabling ip version 6 on the effected windows computers. Similar problems effected internet explorer, Edge and Firefox accessing Outlook.com as well.
Left click on:
Start Orb then, Control Panel then, Network and sharing center then, Change adapter settings
Right click on: Local Area Connection and choose Properties ( with a left click)
Un-check the box that says: “Internet Protocol Version 6….”
Left click: OK
Close any open windows. Try your browsers and test.