Thanks for all the great details! Ya, that would be annoying to wait 15+ seconds for a post to be submitted!
Did anything change on your computer before it started happening? Does the same thing happen from another browser or different computer or even mobile device?
Any other members having this problem? If so, please please see the information here: https://www.backyardchickens.com/a/troubleshooting-byc-problems-bugs-error-messages-other-issues
If none of those things help, please come back to this post and reply with all the information requested in that article above, especially:
1) Which browser and version are you using (eg., Firefox 3.5.9, Internet Explorer 7, etc.)
2) Have you deleted your internet cache / browser history of files and tried again?
3) Have you tried a different browser? This allows you to test if it is a browser specific problem vs. a computer / network problem. We suggest Google Chrome or Firefox.
I just powered down my devices, we'll see if that's it. I do use Google Chrome.