doubts about rc4

Dear Sirs!

Even though I am newbie about crypt., I think my results
are a little bit strangers. I am using avr studio simulator
for rc4. However, the number of cycles are varying as function
of both message size and key size.

Concerning the first, I could notfigure out what is happening, is it
possible? cycles varying with message size?

About the last, at first, I found curious the fact that incresing key
size the number of cycles used to decrease. Afterward, however, I
realized the array has to be filled with the key size and, in turn,
the more is the key size, the lesser is number of instructions to fill
the array. Is that line of reasoning right?

Any help will be very appreciated.

Thanks in advance!

Regards,

     Leonardo

 "N=E3o existe um caminho para a paz; a paz =E9 o caminho"
                                    Mahatma Gandhi