He need to look at where the time is being used.
*How long does it take to read the A/D.
*How long to send the data.
*How long to do what ever else he is doing.

Buffer the data while possibly helpful may not be needed. The A/D could be working while the data is being sent.
He is looking in the wrong place for the solution. A lot of time is being wasted somewhere.

So post code, or look at your time budget.