I'm guessing he's using a variant of his own Qwertuoso program for the playing, and it's tiny, less than 4k. Even with the horribly slow default C64 tape loader

I'm guessing he's using a variant of his own Qwertuoso program for the playing, and it's tiny, less than 4k. Even with the horribly slow default C64 tape loader, that would be about a minute. Linus is one of the demoscene's experts on fastloading too, so he may not use the default loader!