In theory, read-only workload shouldn't have anything to do with
dict_sys mutex. dict_sys mutex is meant to protect database metadata.

But then why does dict_sys mutex shows up as part of a read-only workload?
This workload needs to fetch stats for query processing and while reading
these stats dict_sys mutex is taken.

Is this really needed?
No. For the traditional reasons, it was the default global mutex used.

Based on 10.6 changes, flow can now use table->lock_mutex to protect
update/access of these stats. table mutexes being table specific
global contention arising out of dict_sys is reduced.

Thanks to Marko Makela for his early suggestion around proposed alternative
and review of the draft patch.