Q: Pausing iCloud upload after importing whole library to aperture

Hi - I've just started to use aperture (I never really got on with iPhoto) and I've imported my previous photos (around 5000 in total). However, aperture now seems content with uploading them all to iCloud. This is ok when I'm at work and have a decent connection but at home its killing my internet!

I don't want to stop the auto upload, but is there actually a way to pause the upload whilst I'm at home? I've clicked on Show activity > Pause but I can see the icloud photo's is still uploading data in activitiy monitor! What do you have to do to pause this behemoth?? Why have a pause button that doesn't work!

Thanks

Ben