I often keep my computer on in sleep mode and return to it whenever I need to. Sometimes, resuming it results in a slow down of other processes. For my retina MacBook with a 2.8 GHz Intel Core i7 with 16GB of RAM, I really shouldn't be running into such CPU numbers (unless I'm using a design app).
Naturally, rather than waiting a minute or two for things to cool down, I hit the power button and force reboot the Mac. After that, I noticed my fans whirring up again. Launching Activity Monitor, I found the culprit: Dropbox.
Look at the values of the Dropbox update: 201.7 % CPU, tons of CPU time, 14 threads, and 145 Idle Wake Ups, all for an app update!
I've used Dropbox for several years and I haven't come across this type of bloated activity. What's happening and why isn't this being optimized? I understand the desire to do things silently in order to be unobtrusive (learning from the lessons of Adobe Reader eh?). However, your update is engaging my fans and slowing down the rest of my computer. So much for being out of the way.