When you’re downloading a file with GigaTribe, it is being uploaded by your contact at the same time. Your download speed is as fast as your contact upload speed.
Most of the time, your download speed is limited by your contacts’ upload speed.
If different contacts are sharing the same file, this file will be retrieved from each contact. Your download speed will then be equal to the sum of your contacts’ upload speed. This feature, the multisource download, is only available to Ultimate users.