App freezes for ~30s on servers with many channels.

[Alasofia]

I haven't the faintest clue how many channels this server has, but it lags every time I enter it. Happens every time.
Also, it doesn't lag once it's loaded. As long as I don't enter another server, it is as responsive as ever. Changing to another server and back will make it freeze.

Happy to send an invite to the specific server in question or provide any further assistance, this is the ONE bug keeping me from daily driving Dissent haha.

(Also, sick name choice. Love the app.)

[diamondburned]

This is probably related to #142: Dissent renders threads and forums flat in the tree, and it's not too uncommon for large servers to have hundreds of them at once.

With the thread viewer, we wouldn't need to render all of them in the channel tree anymore.