[maka]

"Pass on to UO" is just an option that you can select for each "play macro" key. Just try the difference when the shard gets up, if you check it, your macro will atelast be 0.2 secs faster.

I'd say that the difference between an injection macro and "Pass on to uo" razor macro is 0.1 sec, but it's kind of hard to give you the exact #.