Define gargantuan. I just opened a 900MB CSV and it choked part-way through and eventually opened after about a minute. Windows 10, 8GB RAM and running on an SSD.

Not to mention if you hit ctrl-f and search for something in the file. Another lock-up for a few minutes while it tries to figure out highlighting. This is something I've reported to them. I have never considered Sublime to be a good handler of large files.