It's interesting though why cross-process data exfiltration based on speculative execution was not tried with any success in the shared hosting environment of 1990s and early 2000s. I suppose it has something to do with the use of non-JIT-ted interpreted languages, like PHP, Perl, or SQL, on such hosting; you could not run an arbitrary native executable like you do in the cloud.
Another factor is that though speculative execution was first implemented in 1950s [1], it was either mainframes or RISC machines, and neither was used by the Intel-dominated shared-hosting environments.
