Interesting, didn't even know you can cut files from a zip in that Windows zip file viewer. I would have thought it's some read-only filesystem like viewing a mounted CD or so. In that context I wonder if you could cut from rewritable CD-RWs as well back in the day (can't remember) - that seems like another abstraction that's similarly slow in reality.
I never tried cutting from CD-RW, but AFAIR each burning would append a non-trivial header (like 20MBs or so) so that would be a pretty expensive thing to do :) AFAIR when you "copied" into CD-RW the files would show up semi-transparent (pending) and you'd have to click a button to process with burning. Probably same for cutting I guess.
Been years, but the ISO file system says 16 sectors past the start of the last track is where the file system index starts. (the first 15 sectors are reserved for booting) Then however many sectors you need for the index - which depends on how many files you have, and how long the filenames are. Note that both CDR and CDRW don't allow you to write sectors in the middle of a track, so you need to know where every file will be on disk before you can write anything - you can't build the index on the fly. (I remember this part because I was writing backups and so I didn't know how big the file would be until I was done and thus couldn't write the index first - I eventually got around the rule by creating a new track with just the index)