Improve site performance

[wang-arthur]

See https://pagespeed.web.dev/analysis/https-post45-org/qgubdgaibb?form_factor=mobile for suggestions on reducing load times

[wang-arthur]

Switch to headless WP backend + static site generator (Gatsby?)

[wang-arthur]

Should be fixed once we migrate site to a static site generator (https://github.com/Post45-Journal/Projects/milestone/3) on Azure (#39)

[wang-arthur]

Migrate website from WordPress to a newer CMS & static site generator