If you use ssh a lot with zsh and have a lot of entries in your hostsfile (/etc/hosts) you might find it convenient to disable completion from these hosts by using:
zstyle ':completion:*' hosts off
However, this may give you adverse affects, and your hostnames may stop auto-completing with rsync – in order to fix this try also adding this in to your .zshrc
zstyle -s ':completion:*:hosts' hosts _ssh_config
[[ -r ~/.ssh/config ]] && _ssh_config+=($(cat ~/.ssh/config | sed -ne 's/Host[=\t ]//p'))
zstyle ':completion:*:hosts' hosts $_ssh_config
If you also use oh-my-zsh and are still having trouble, trying adding those lines after this line:
source $ZSH/oh-my-zsh.sh
Exactly what I was looking for, thanks!