The Network sub-tab can be found within the Preferences window.
Within the Network sub-tab you can find several relating to the use of HTTP proxies and limiting your bandwidth usage. We do not recommend working in this sub-tab unless you are already experienced with networking protocols and behavior.
If you do feel confident with these sorts of procedures, check out the Connecting to SpiderOak using a Proxy Server article
This option is disabled by default, because ONE will automatically evaluate the bandwidth needs of your other applications and scale back its own consumption to not hamper your activities such as using web browsers or mail clients. If ONE's automatic scaling does not suit your needs, feel free to experiment with this setting.