Yeah, I did create the guest account and everything is running a lot better than it did. I still see beach balls but many other issues have sorted themselves out.
Thanks, bedifferent. Between your suggestions, information and other folks easy to follow instructions, I'm hoping for another few months out of this iMac now.
That's actually great news! So something in your home /Library folder is causing those issues. I would create an admin account, copy your personal documents over, and delete the guest account. Use that new admin account as your main account.