## Tracer
### Changed
- Reduce integrations overhead #3380
- Avoid unnecessary gc_collect_cycles if there's no open span #3428
- Make use of fast_shutdown to avoid freeing overhead #3429
- Optimize PDOIntegration::parseDsn() #3430
### Fixed
- Fix #3135: Force flushing on shutdown of entry point processes #3398
- Support curl_multi_exec root spans #3419
- Fix a couple memory leaks #3420