Motorola Droid :: Battery Life Suddenly Cut In Half

I suspect many of you are like me and monkey with your phones so damned much that sometimes it's hard to pinpoint what changes we've made to which changes we've noticed. I've been running UD 9.0 ever since it came out. I've had great battery life with SetCPU profiles set from 250MHz to 1Ghz unless the battery goes below 30%, in which case it goes down to a max of 550MHz with a low still at 250MHz. The only thing I've changed recently is downloads of app updates, (...including SetCPU, btw). The other day my home WiFi crapped out, so I used a tether app and played around online with my laptop using my phone. I had never done it for so long before, but inside of about three hours, my battery was at 20%, when usually at that time of day, it's at hour 13 from last charge, and at about 40%. Now my battery is not lasting a whole 14 hours, where it used to go from 5 AM to 10 PM before it gave me the "15% juice left" heads up. I don't know if it's because of a bad SetCPU update, or a wifi tether app problem, or what.