Currently, a signaled vertex reads the state of the relationship field through which it was signaled upon signal receipt. This makes signal propagation toward high-cardinality relationships (e.g. members on roles) un-performant; if this read could be removed, signals could be propagated everywhere across the graph with minimal cost.
I think this read is part of the 'triggerSyncCheck' legacy and is no longer necessary.
This Jira covers investigating this possibility, and devising a compatibility scheme for functionality still dependent upon this read state.