RocksDB Compaction filter to clean up state with TTL

[Seth, Abhilasha]

Hello,
Flink 1.8 introduces the config 
‘state.backend.rocksdb.ttl.compaction.filter.enabled’ to enable or disable the 
compaction filter to cleanup state with TTL. I was curious why its disabled by 
default. Are there any performance implications of turning it ON by default?
Thanks,
Abhilasha