Question:Pam Achas Bikesh Agrippas...Vnimtzoh shom 600,000 zugei kloyos. If we do some arithmetic, 1 hr = 3600 seconds; if the shechitah process took (let us say) 2.5 hrs, that would be 9000 seconds. That would mean that the Kohen Godol (or agent) handled -and the gemarah goes to detail to show that the procedure was one that he HANDLED each pair of kidneys- 600000/9000 or 67 kidneys/second! Humam hands (brains?) are incapable of moving at that speed.
Interesting question. The answer is that the Kohen Gadol did not do this counting procedure personally. Although it was the Kohen Gadol whom Agrippas told to count the Jews, that does not mean that the Kohen Gadol did it personally. Rather, the Kohen Gadol was the representative of the Jewish people in the city and thus he was the one to speak to in order to issue an order to count the Jews. The Kohen Gadol then went and organized a committee of Kohanim and instructed them how to conduct the census. Those Kohanim then brought the numbers they counted to the Kohan Gadol (or his agent) who simply added them up to get a total number.
Therefore, in your equation, you should divide the 600,000 pairs of kidneys into, let's say, 1000 Kohanim (it could be that they started with less and added more as they saw the need to), and thus each Kohen counted 600 pairs. In your figure of 2.5 hours, that comes out to 4 pairs per minute, which seems reasonable.