As ozgune just said: yes, that's right. The 9X is a comparison of how Postgres stored procedures in Citus 9.4 perform vs. in Citus 8.3 (as measured by the HammerDB benchmark, shown in Figure 5.)

When I read this post, I find the HammerDB TPROC-C benchmark results in Figure 1 to be super interesting, too. When you compare Citus 9.4 performance with distributed tables and distributed functions vs. Citus 9.4 with regular Postgres tables and regular Postgres functions (on a single node) -- then the multiplier is an even more impressive ~19X. :)