Update DB Query fails sporadically when saving contact; nativecode=1205 ** Lock wait timeout exceeded
We have seen this on large instances. Things to do:


upgrade to 5.13.5 (this also puts you close to the next ESR - a paid for service - which will be released on Nov20).


There have been performance improvements - this will help.


cull your smart groups; do you really still need all of them.
reschedule the cron job -> ask yourself how up to date your smart groups need to be.