I didn't get everything here and I only made this a quick edit in the browser (not tested), but hopefully this should speed things up for you. Tests will need slight updating too, but just see the linked wiki page for more information on how to do that. Let me know if you have any questions!
According to: https://github.com/mholt/caddy/wiki/Converting-Add-ons-to-Plugins
I didn't get everything here and I only made this a quick edit in the browser (not tested), but hopefully this should speed things up for you. Tests will need slight updating too, but just see the linked wiki page for more information on how to do that. Let me know if you have any questions!