[jimsmart]

> The c64 could decompress the data faster than the Datasette could play it back, so there was no processing wait.

C64 fast loaders generally didn't use any compression whatsoever.

They would cut the load time in half by simply only writing/reading the file once (whereas normally the load process actually read the data twice) - and then get extra a whole heap of extra speed on top of that (turbo speed!), by implementing the load in custom code, basically working at a faster baud rate than the standard C64 kernel code did.