hey marco,
mark provided a fix for the cover issue here: http://stackideas.com/forums/problem-with-cover-uploads-in-profile-and-groups

Hi alex please provide mark about the uploading time.

Anything needs time here so the uploading of small 100kb images is very slow

Hello Marco,

I am sorry for the delay of this reply.

Regarding your issue with slow upload, I suspect is the connections made to your server during the upload and causing the slow issues. When you upload a file, it send the image to your server. If the connection to your server slow, it take time to perform the uploads. Also, uploading photo is a heavy process because when you upload one single file, in your server it actually created few photos with different sizes for later use. Each photo creation might take some time to process thus when you upload photos in bulk, you might see some slowness.

Hope this help and have a nice day