Per someone else's suggestion on a similar thread, I deselected the mail >preferences >accounts >advancedMail > Preferences > Accounts > Advanced > Automatically detectDetect and maintain account settingsMaintain Account Settings and mythe CPU dropped back to normal range. I have 3 google, 1 yahoo, and iCloud accounts involved. Hopefully Hopefully this fix will stick. I had run Disk Util multiple times for same issue, and there seem to be continual permissions errors popping up, so not sure if another underlying process or this was it. Good luck!