They become quite long, but it was surprisingly tolerable. I recall it vaguely but a 100MB neural network was on the order of minutes with all optimizations turned on. I guess it would be fair to say it scaled more or less linearly with the file size (from what I saw). Moreover I work in essentially a tinyml field so my neural networks are on the order of 1 to 2 MB for the most part. For me it wouldve been reasonable!
I guess in theory you could compile once into a static library and just link that into a main program. Also there will be incremental compilation in zig I believe, maybe that helps? Not sure on the details there.