you didn't precise that you are using godaddy's webmail (mail server). i understood from what you wrote that you are only using godaddy for the domain (glue records/name servers) and that you are using your own server for email. The idea was implied when i wrote you need to verify your mxrecords.
it wasn't high. actually it have always remained stable. tags weren't only shown in a tag page, they also appeared in forum list view and topic view.
I can assure you with certainty that tags when correctly configured increases search engine traffic.