You can try VoltaicHD, another pay-for ffmpeg-based program - I've had luck with that myself but it's still slow.
The fastest in my experience is using iMovie or Final Cut Pro's built in importer. You can import the files without plugging in the camera by doing either of the following:
Copy the entire AVCHD folder (not just the .m2t files - it's important to have all the folders and relevant metadata in the folder structure) to your hard drive and then point Final Cut Pro's Log and Transfer at that folder
OR
Create a disk image of the camera using Disk Utility. Once completed you can unmount the camera and mount the disk image and as far as iMovie and Final Cut are concerned it's just as if the camera was plugged in and they'll auto detect the footage.
To create the disk image, choose "New Disk Image from <NAME OF CAMERA> (eg. NO NAME)" in the File menu.