slow DB query performance with cm_identifiers table

I am seeing slow performance with a DB query against the cm_identifiers table with a query that is run multiple times during an Org Identity Source pipeline when creating a new COperson.

Below is the query. For one new person, this query was run 12 times with various co_group_id in the WHERE clause.  I saw 4 different co_group_ids used, and each one was queried 3 times.

SELECT "Identifier"."id" AS "Identifier__id",
"Identifier"."identifier" AS "Identifier__identifier",
"Identifier"."type" AS "Identifier__type",
"Identifier"."login" AS "Identifier__login",
"Identifier"."status" AS "Identifier__status",
"Identifier"."co_person_id" AS "Identifier__co_person_id",
"Identifier"."org_identity_id" AS "Identifier__org_identity_id",
"Identifier"."co_department_id" AS "Identifier__co_department_id",
"Identifier"."co_group_id" AS "Identifier__co_group_id",
"Identifier"."organization_id" AS "Identifier__organization_id",
"Identifier"."source_identifier_id" AS "Identifier__source_identifier_id",
"Identifier"."co_provisioning_target_id" AS "Identifier__co_provisioning_target_id",
"Identifier"."created" AS "Identifier__created",
"Identifier"."modified" AS "Identifier__modified",
"Identifier"."identifier_id" AS "Identifier__identifier_id",
"Identifier"."revision" AS "Identifier__revision",
"Identifier"."deleted" AS "Identifier__deleted",
"Identifier"."actor_identifier" AS "Identifier__actor_identifier"
FROM "public"."cm_identifiers" AS "Identifier"
WHERE "Identifier"."identifier_id" IS NULL 
AND "Identifier"."deleted" IS NOT true 
AND "Identifier"."co_group_id" = 5;

Creating an index on the co_group_id column in the cm_identifiers table resolves the performance problem.  This query goes from taking 5-6 seconds to execute down to milliseconds to execute.

example SQL I used to create the new index:

CREATE INDEX cm_identifiers_wfu_i1 ON public.cm_identifiers USING btree (co_group_id);