Lot of OneDrive (SkyDrive) users reported this issue. OneDrive upload speed extremely slow. But you can increase OnDrive upload speed with some settings.
Increase or decrease OneDrive Upload Speed (Windows)
Right click OneDrive icon in the notification area on the taskbar (right side) -You may need to choose Show hidden icons to view all icons.
Click Settings and choose Performance tab.
Uncheck the box next to Improve upload speed by uploading files in batches.
How to increase or decrease OneDrive Upload Speed (Mac)
Click OneDrive icon in the menu bar and choose Quit OneDrive option to shut down OneDrive.
Type or copy paste the following command in Terminal : open -a TextEdit ~/Library/Containers/com.microsoft.onedrive-mac/Data/Library/”Application Support”/OneDrive/settings/global.ini
It will open global.ini file in the editor.
Here you can set the concurrent uploads value to either 1, 2, or 3.
Example : add the line numberOfConcurrentUploads = 2 as a first line in the document (Ensure that line isn’t already present anywhere in the file. Because it will prevent OneDrive from working. Also do not change any other lines in the document).
Choose File -> Save option in the Text Edit.
Now start OneDrive via App folder.
Increasing this value from its default of 1, will increase upload bandwidth on your computer.
Note : If making this change negatively impact your devices on the local network, change the value back to default 1.