you dont need a computer. just insert your sd card inside your box, open up browser on your box and download into your sd card or use TeamViewer to transfer files from your cell phone to your sd card in your box.
many ways to do it without computer.
as far freezing im hoping no one is using your credentials same time you are watching which mostly evening time. if thats the case then you might see freezing because two connections same time. I use a lot like that and when I notice second person gets connected it start to freeze or lag until one of us leaves.
I'm using 1 Mac based and 45 XC API servers and my cache data is at 3.86 GB. I never cleared and its been like this from some time and I have delete 20 servers between lol
that could be servers related issues. Before even update I had few servers would take forever to load while others were quick. had few crashed but then I got rid of those servers and never had that issue. one of the server would take forever but I just tried 4 days ago after long time and it started to work fast now. so I believe its more server related but you never know.