Old Canon D30 and Sigma "Bigma" 50-500

Hello everybody.

I still have old Canon D30 and I' considering buying the Sigma 50-500 for
that camera. How do you think: will it focus very slow on D30 ? If yes, I
should rather consider buying a new body... Maybe someone remember how it
worked with D30 ? I've got Sigma 24-70 3.5-5.6. I know it is not a top lens
but it is fast enough for me and I would be pleased if the big sigma focused
with similar speed. I've got also Canon 50mm 1.8 and speed of its focusing
is a nightmare. It rotates few times before focus. It is strange for me
because that lens is very bright so it should be faster.

Thank you in advance for all your advices.
CMP