Forum Discussion
Sharepoint Online Throttling
When uploading a single folder through the web interface, you can get throttled if that folder holds a large number of files. I'd suggest you update the web interface for Sharepoint to slow down ...
Microsoft don't on the whole monitor these discussions, you would be best of reporting a ticket in the Office 365 Admin portal.
If you are having issues uploading through the browser then a work around, and the best way to do it generally would be to sync the destination location to your desktop and then drop the folder into that location. The Sync client is intelligent with your bandwidth and will upload the documents in the background.