We got a performance regression from bug 7379 where the Linux client stopped using shared memory for graphics updates. This can result in excessive CPU usage and possibly poor performance. Already fixed upstream though: https://github.com/TigerVNC/tigervnc/commit/0f1ded057dbf875e69a0d72418d95610db8fa6a3
Issue originally reported here: https://groups.google.com/forum/#!topic/tigervnc-devel/RDmrc0memIc Unfortunately he did not describe the scenario where he saw this.
This doesn't seem to have any major effect on performance as we cannot see any clear difference in CPU usage between versions that have this bug and those that do not. However I can see in /proc/<pid>/maps that the fixed versions have a shared memory segment, and the broken ones do not. Using "perf" I can also see __memmove_avx_unaligned_erms using 6% CPU as a result of XPutImage() being called (instead of XShmPutImage()). I suppose that will have to be good enough testing. Not making a release note as the difference was so small.
