Mac os x

Save screenshots as jpg

defaults write com.apple.screencapture type jpg;killall SystemUIServer

time

 sudo sntp -sS time.apple.com

Change default screenshot filename

defaults write com.apple.screencapture name "iDB"
killall SystemUIServer

Spotlight

Kill it: add the HD to privacy, in apple system settings

Restart, Command+r, shell, then:

csrutil disable

Then, unload the service:

 sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist