Private Proxy loading very slow or not loading at all. HELP ME!

Has anyone had an issue like this? I've tried two different private proxy providers, 3 browsers, 2 different internet connections, cleaning all cookies and still "Connecting..." loads for few minutes till it ends with a white page..

Please help me if you have any tips!

What's your internet speed? You can have the fastest proxies in the world, but if the connection behind them is shit it won't help/matter.