- Gateway project scope instead of gateway global scope.
- Option for a dedicated thread.
- Single event script can run multiple queries in any desired order, writing results to memory tags with any desired timing.
- Event scripts can post-process results before writing to tags, relieving the DB of static joins and other lookups. Including using cached lookups.
- Event scripts can drive multiple target tags from single, larger queries.
- Event scripts can simulate joins across datasources.
- Easy parallelism control with separate event scripts.
- Even when not using a dedicated thread, gateway events use a different thread pool than tag groups and tag events.
Edit:
9) Tag groups (and v7.9 scan classes) are operationally opaque–very un-fun to troubleshoot.