I did a rudimentary benchmark on the same 8-node Sun Fire X4600-M2, on top of todays 5.11.0-rc7-00002-ge0756cfc7d7c.
The test: building clean kernel with make -j64 after make clean and drop_caches.
While running clean kernel / 3 tries):
real 2m38.574s user 46m18.387s sys 6m8.724s
real 2m37.647s user 46m34.171s sys 6m11.993s
real 2m37.832s user 46m34.910s sys 6m12.013s
While running patched kernel:
real 2m40.072s user 46m22.610s sys 6m6.658s
for real time, seems to be 1.5s-2s slower out of 160s (noise?) User and system time are slightly less, on the other hand, so seems good to me.