[jpegqs]

> Is the rest of the table[1] unchanged?

The rest is unchanged, but there is a trick in that the table indexes are shuffled, and shuffled differently depending on the neighboring values in a 24-bit block of source data.

> but I have had to decode a ton of 64-bit base64 strings, for example

Should be good for small data. It's a pity that no one (or I haven't seen such benchmarks) measures the performance of decoding a large amount of small data (like 1..64 bytes).