This is a little weird where the J2dBench-bimg_misc* got a similar boost in performance that I tracked back to JDK-8316893 in b18.
Now, a couple builds later the perf returned to let's say the b17 baseline level. I did CI build by build tracking and this seems to be introduced with JDK-8305321. This only happened on ARM so it might be a platform quirk. These are run on OCI A1.160 with numactl on node 0.