Just have some patience. If you've got all your options to download turned on, then turn some off. (I keep shapes and textures on as I hate seeing the default-item in place of new ones).
If the server you're trying to connect to has RTB, then go back to the server list, find the server and click the 'Information' button (If you have RTB) and then download the Add-Ons directly from there. That will save you a lot of time when you reconnect to that server.
If you aren't going to download Add-Ons yourself from either the Forums or using RTB in-game and would rather wait for the game to download them from the server (even though it takes a heck of a lot longer) then just try and do something else. Pick up a handheld game, do something constructive, go play outside or with some other toy, watch a little television. Just because you're downloading Add-Ons doesn't mean you have to be there for the entire thing. But, it's a very very nice idea to tell the host that you may be Afk until you finish loading. And, try to regularly look/listen for when you've finished loading. If you're still in the same room, it's best to have the sound on so you can hear the Ghosting sounds when you spawn or whatever sounds can be heard.
And if that's such a nuisance, then just host your own server. I'm sure you can find something fun and interesting to do on your server. And, the moment you get one person to join your server who plays on it well, you won't need to wait long at all. If one person joins, then you'll attract more people. Just give it a little time and you'll probably get regulars and a nice enough traffic through your server. Just, don't be worried if you get off-days where no one joins.
