I realized the other day that on OS X, the Spotlight indexing process is started using launchd. This makes it very easy to modify the launchd configuration script to insure that background indexing uses the least amount of CPU and I/O bandwidth possible.
Edit the configuration script by running this command as root:
# open /System/Library/LaunchDaemons/com.apple.metadata.mds.plist
You should find yourself in the Property List Editor application. Now add two keys at the top-level, one named LowPriorityIO, which is a boolean set to true, and another named Nice which should be an integer set to 20.
Now whenever the mds spawns mdworker processes to index recent changes to the file system, it won’t get in your way quite as much as before. (Without this change, mdworker processes run at the same priority as user processes, according to output from the ps axl command).


Nice tip. But how exactly do you suggest running this command as root? su open … ? sudo, then … ? The pretty Property List Editor would not let me save the file, so I dropped into vi (shudder). That worked.
error between chair and keyboard? http://thumbsnap.com/v/TalA5pgC.png
You can put sudo in front of John’s command. To let you save from the Property List Editor just “sudo chmod o+w com.apple.metadata.mds.plist” beforehand. Don’t forget to give yourself write access on the directory, too, and remove the write access from both when you’re done. You’ll also need to change the file ownership back to root, as the save will make it yours.
any suggestions?
and then
this worked for me