Welcome to StackExchange! Based on the question from my understanding the application is slow because the gpg keyring is not connecting to a tor relay if I understand correctly.
There are multiple factors that can cause the keyring to not be responsive though most of them may be out of your control.
To start off with the more basic problems, are you sure that nothing is blocking your connection to the torprojects entrance node? such as a firewall rule, VPN, DNS filter, etc.
Also, you can check the status of all the tor relay nodes with https://torstatus.blutmagie.de/, you may be entering through a bad node if so reset your connection.
If it is none of the above it may be a problem associated with where the key is trying to connect, You can manually install the tor browsers repository straight from the website, here's a quick script that can do that automatically:
echo "deb https://deb.torproject.org/torproject.org stretch main" | sudo tee -a /etc/apt/sources.list
echo "deb-src https://deb.torproject.org/torproject.org stretch main" | sudo tee -a /etc/apt/sources.list
sudo add-apt-repository ppa:webupd8team/tor-browser -y
sudo apt-get install tor-browser -y
apt install torsocks
apt install tor-geoipdb
deb https://deb.torproject.org/torproject.org $V main
gpg --keyserver keys.gnupg.net --recv 886DDD89
gpg --export A3C4F0F979CAA22CDBA8F512EE8CBC9E886DDD89 | sudo apt-key add -
apt-get install deb.torproject.org-keyring
apt install tor -y
after this has been executed it should work back to normal, I hope this may help you.