These typically work by changing the media bit encoding to be easier to process with 6502 instructions instead of a lookup table. Others simplify the table and use more RAM so that fewer lookups are needed. I haven’t looked at how Transwarp works yet but it seems like the latter.

Some discussion with the author: https://www.lemon64.com/forum/viewtopic.php?t=78558&start=0

There’s a newer version here: https://csdb.dk/release/?id=214786

Release notes: https://csdb.dk/release/?id=214786&show=notes#notes

More details from another advanced loader:

https://www.linusakesson.net/programming/gcr-decoding/index.... https://www.linusakesson.net/software/spindle/v3.php