Couple of information on the current stage of things. With regards to SMP, the situation has definitely improved since last releases, however, things starts to go bad as soon as the world becomes reasonably complex. I’m working on getting decent reproducers to investigate, but please be patient. If you experience any problem, please make sure that you do get a backtrace otherwise reporting is just useless.
Other point, the world contest. Deadline is extended until October 31st. Last days to finish your work or re-submit an updated version!