Hide the join/part/quit messages. If your IRC channel is busy you’ll know how annoying these are. The xkcd wiki has instructions for other IRC clients.
All channels: /set irc_conf_mode on
One channel: Right click on a channel, “Settings->Hide join/part messages” (src)
Hide the “UserX is known as UserY” messages. Users have scripts or use ZNC that will rename themselves when they go away or disconnect from the proxy. On a busy channel this can generate a huge amount of text.
Settings > advanced > text events
highlight “change nick”
in text box below, highlight that text and delete
click “ok” (src)
Many more tips here of course but I think the first tip above is the most useful, at least for me!