I've played with this and am not getting anywhere near the -Xmx set for the JVM and producer flow control isn't kicking it. Load on this broker isn't very high

I've played with this and am not getting anywhere near the -Xmx set for the JVM and producer flow control isn't kicking it. Load on this broker isn't very high either, 5k to 10k messages/day, all messages << 1KB.