Office 365 contains a light version of the Outlook on the Web that is useful to those with slower connections, older internet browsers, or accessibility needs.
1. From the Outlook app, click the gear icon in the upper-right corner of the screen and search Outlook on the Web version. Click on the Outlook on the Web version button that pops up.
2. Click the checkbox next to "Use the light version of Outlook" and click the Save button.
3. The next time you log into Office 365, it will load the light version displayed below.