Switching from Yahoo Mail to Yahoo Mail Basic will give you a cleaner, faster loading interface. This can be helpful if your internet connection is slow, you’re having issues with your browser, or you just prefer a simpler experience.

Yahoo Mail automatically switches to Basic mode when it detects a slow connection or a browser that doesn't know how to use the full interface. However, switching manually requires a few steps:

Click on the 'Settings' gear.

Select More Settings from the drop-down menu.