Poor MacBook Battery Life Caused by Time Machine?

My MacBook is my second computer, and I don’t use it much. I use it for testing, for taking screenshots, and for working outside my office from time to time. I’ve been using it a lot in the past week, and I’ve noticed that I’m getting perhaps 6 hours of battery life, without using a lot of apps.

One thing I notice is that two processes, mtmd and mtmfs, pop up frequently, using about 100% of CPU (of a core) and do so for a while. Here’s a screenshot from iStat Menus when that happens:


These two processes are related to Time Machine, and have something to do with creating local snapshots. But I’m only using the MacBook at my home office, so it’s on the network where my Time Machine backup device is located, and it shouldn’t make local snapshots. It should only do this when it can’t access your Time Machine disk; it then copies those snapshots the next time the Time Machine disk is available.

When I check Activity Monitor, and look at Energy, the app listed as having the highest impact is Time Machine, way above Safari which is the second. So it’s clearly Time Machine that’s killing my battery.

Activity monitor

I’ve contacted AppleCare, and spent a lot of time on this, sending them logs and other data, and I’m waiting to hear back. I reinstalled El Capitan, and nothing changed. Is anyone else seeing this?

Update: I found the following in system logs. I find these entries to be interesting.

12/7/15 18:32:47.000 kernel[0]: Sandbox: mtmfs(552) System Policy: deny(1) forbidden-rootless-xattr
12/7/15 18:32:47.156 mtmfs[552]: could not set attributes com.apple.rootless on destination file descriptor: Operation not permitted: Operation not permitted

12/7/15 19:33:33.810 com.apple.xpc.launchd[1]: (com.apple.mtmfs) Unknown key for Boolean: ForceEnableHack
12/7/15 19:33:33.810 com.apple.xpc.launchd[1]: (com.apple.mtmfs) This service is defined to be constantly running and is inherently inefficient.