If Mavericks feels sluggish, these defaults write commands reduce lag by tweaking system timeouts and disabling Finder app sleep. Quick fix for old installs.

sudo defaults write /System/Library/LaunchDaemons/com.apple.coreservices.appleevents ExitTimeOut -int 1
sudo defaults write /System/Library/LaunchDaemons/com.apple.securityd ExitTimeOut -int 1
sudo defaults write /System/Library/LaunchDaemons/com.apple.mDNSResponder ExitTimeOut -int 1
sudo defaults write /System/Library/LaunchDaemons/com.apple.diskarbitrationd ExitTimeOut -int 1
sudo defaults write /System/Library/LaunchAgents/com.apple.coreservices.appleid.authentication ExitTimeOut -int 1
sudo defaults write com.apple.Finder NSAppSleepDisabled -bool YES