Disable Self-Pingbacks
Stops WordPress from sending pingbacks to your own site when you link to your own posts, so they do not clutter the comment queue.
Snippet Library
Comments snippets for WordPress
Snippets for WordPress comments: fight spam, close comments on old posts, remove the website field, change the comment form and moderate faster. For bloggers and publishers who want useful discussions without the noise.
Move the Comment Box Below the Name and Email Fields
Reorders the comment form so visitors fill in their name and email before writing the comment, the order many themes used before WordPress 4.4.
Stop Saving Commenter Details in Cookies
Stops WordPress from remembering commenters' name, email and website in cookies, and removes the related consent checkbox.
Stricter Comment Flood Protection
Requires a longer pause between two comments from the same person, 60 seconds instead of WordPress's 15, to slow down comment bursts.