Because it's taken out of the context. Original text says: "We even observed that ngx_drizzle + ngx_rds_json achieved 128MB/sec (Yes, 1024Mbit/sec!) for a 380K

Because it's taken out of the context. Original text says: "We even observed that ngx_drizzle + ngx_rds_json achieved 128MB/sec (Yes, 1024Mbit/sec!) for a 380KB data-set query while connecting to a simple mysql server, about 3 ~ 4 times as fast as php + libmysql in this setting." As you can imagine in such scenario (380KB result), MySQL engine is taking the most of the time.