I use Keyboard Maestro often in conjunction with AppleScripts to make my life easier. One of my favorites is the keystroke <cmd-b> to open files with BBEdit.
Under 10.8, AppleScript and the Finder are ridiculously slow -- "get selection" takes about 5 seconds per item selected to return a list of items selected.
The solution? Change it to "get selection as alias list". That returns the list instantaneously, and seems to work about the same in most cases.
Here's the script if you're curious (view on blogger, not feedly, to see the script correctly):
tell application "Finder"
set theApp to application file id "R*ch"
set theFiles to (get selection as alias list)
if (count of theFiles) > 0 then
open theFiles using theApp