I usually upgrade to a new OS X about one year later than the official release. That’s why I only recently hit the problem of an extremely slow time machine backup. After some digging to find a solution, it was the trick described at OS X Daily’s Speed Up Time Machine by Removing Low Process Priority Throttling that fixed the problem for me.
After a reboot the fix must be manually repeated, which I am only reminded of by noticing a backup that started the previous evening still not being past likt 5%. (I am using TimeMachine Editor to schedule backups outside of office hours)
OS X Daily also describes how to permanently set this sysctl configuration parameter, with the notice: for advanced users only since it as same caveats. Read their article if you’re unsure!
cd /Library/LaunchDaemons/ wget https://gist.githubusercontent.com/ypujante/e85a9e5284b7e5f397aa/raw/08f620915e0175ceadec0d7e5c68c6b86f3c8424/fix-el-capitan-slow-time-machine-speed.plist
and check the result that should look like the following:
cat fix-el-capitan-slow-time-machine-speed.plist <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <!-- Copy under /Library/LaunchDaemons and issue sudo launchctl load /Library/LaunchDaemons/fix-el-capitan-slow-time-machine-speed.plist --> <plist version="1.0"> <dict> <key>Label</key> <string>fix-el-capitan-slow-time-machine-speed</string> <key>ProgramArguments</key> <array> <string>/usr/sbin/sysctl</string> <string>debug.lowpri_throttle_enabled=0</string> </array> <key>RunAtLoad</key> <true/> </dict> </plist>