I always found that my SC-2 performed sluggishly or erratically.
I remedied this by running an earth ground wire near it. (Just a length of stranded, copper wire that has one bare end wrapped around the water pipe in our basement.
This improved the reliability and reaction.
Also, are you using the Legacy remote to activate the SC-2? I I ask as I believe it has a "route throw rate" adjustment but that shouldn't come into play here.