In terms of space usage and its impact on the buffer pool, storing as 128-bit integers (if your DBMS supports it, which MySQL does not) is essentially equivalen

In terms of space usage and its impact on the buffer pool, storing as 128-bit integers (if your DBMS supports it, which MySQL does not) is essentially equivalent to the bin16 case in the first "UUID insertion rates" graph. Performance still falls off a cliff, just a little bit later. As the author says, "The use of a smaller representation for the UUID values just allows more rows to fit in the buffer pool but in the long run, it doesn't really help the performance, as the random insertion order dominates." If you look at the fastest approach the author tried in the second "UUID insertion rate" graph, it actually stores a modified UUID in a 36-character string. There is a missed optimization to store the modified UUID as 16 bytes, rather than 36, but imposing some order on the keys is the dominant improvement.