&gt; had upgraded to El Capitan. That day I had 50gb of traffic on my network. Typically 2.5-5 or less.<p>After upgrading an iMac to OSX El Capitan the Photos.app decided to upload all photos on the iMac to iCloud. I consider it to be a bug since all photos on the mac originally came via iCloud from my iPhone. Seems unnecessary for Photos.app to upload every single file again, but it did.<p>Network bandwidth was saturated (high packet loss, almost useless) for a few days until Photos.app was done uploading.