I had something similar a few years ago. I ended up having to write a little script to pull out just the channels I wanted as nothing could handle the 18 thousand stream options it provided (total insanity that its bundled up into 1 file like that in the first place but seems to be the norm for dodgy IPTV providers).

Nowadays theres better tools for the job. StreamMaster* for example can handle thousands of IPTV sources and let you organise them nicely into something that can be read by Plex, Jellyfin, etc.

*Sadly recently abandoned but still available on github.