Sigma 30mm slow for others?? (not an f stop rant)

I use the sigma lens with a nex c3 and have noticed it is slower to start up, and flick between pictures. Sometimes taking a good few seconds to start. When I put the kit lens back on, it's much quicker. The thing is, I will put up with the sigma because I really like the image quality from it, and it's easier to carry around in my coat pocket.