The Nikon 4000 has automatic feed, but you need the right carrier for it, or you can modify one which is easy to do. I've beed using one for many years. Still going strong. It takes roughly 40 or so minutes to scan a roll of 36 with Vuescan if you keep the settings simple. I've done somewhere north of 40,000 scans with it.
If you use it with Vuescan, you can set it up to scan the film as soon as you insert it.
If you want a fast scanner the only ones are the minilab scanners. Those have gotten expensive though, and the quality isn't as good.