Thanks very much, Aaron, for your answer!

Thierry
You are effectively doing a multi get. Getting more than one row at a time is normally faster, but there will be a drop off point where the improvements slow down. Run some tests. 

Also consider that each row you requests creates RF number of commands spread around the thread pools for the row. If one client req requests 100's or 1000's then this can delay other client requests. 

Cheers