Does IFS have any performance benefit (i.e. faster uploads for large files)? Or is it just to compensate for slow/unreliable connections?
It is meant to compensate for network limitations when uploading large files in addition to working around service file size limitations. There are performance benefits by way to more efficiency and the ability to resume, but speed should be approximately the same.
Thank you. Would IFS get around the Box 15GB single file size limit?
Yes. IFS would split the file up into segments, each one well within the Box limits for single file size.