1. Check the size of the file you’re trying to upload and see if it’s within the acceptable limits according to the OneDrive service provider.

2. Check your internet connection and speed. Weak connections or slow speeds can affect the overall speed of the uploads and downloads.

3. Check if your device supports OneDrive and if there are any related updates.

4. Try disabling your antivirus software temporarily to see if it's blocking the service.

5. Try to upload and download files one at a time. Uploading or downloading multiple files could be causing the delays.

6. If possible, try uploading the files through another device.