# Which Problems Are Solved
When executing many concurrent authentication requests on a single
machine user, there were performance issues. As the same aggregate is
being searched and written to concurrently, we traced it down to a
locking issue on the used index.
We already optimized the token endpoint by creating a separate OIDC
aggregate.
At the time we decided to push a single event to the user aggregate, for
the user audit log. See [technical advisory
10010](https://zitadel.com/docs/support/advisory/a10010) for more
details.
However, a recent security fix introduced an additional search query on
the user aggregate, causing the locking issue we found.
# How the Problems Are Solved
Add a feature flag which disables pushing of the `user.token.v2.added`.
The event has no importance and was only added for informational
purposes on the user objects. The `oidc_session.access_token.added` is
the actual payload event and is pushed on the OIDC session aggregate and
can still be used for audit trail.
# Additional Changes
- Fix an event mapper type for
`SystemOIDCSingleV1SessionTerminationEventType`
# Additional Context
- Reported by support request
- https://github.com/zitadel/zitadel/pull/7822 changed the token
aggregate
- https://github.com/zitadel/zitadel/pull/8631 introduced user state
check
Load test trace graph with `user.token.v2.added` **enabled**. Query
times are steadily increasing:
Load test trace graph with `user.token.v2.added` **disabled**. Query
times constant:
---------
Co-authored-by: Livio Spring <livio.a@gmail.com>
63d733b3a2