Monitor with SDK v2 performs much worse under high TPS

[xin-hedera]

Detailed Description
Monitor (>= 0.29.0) with SDK v2 can't reach target TPS in GKE with resource limit (cpu=1.75, memory=4G). With previous monitor, a single pod can reach and sustain 1500 TPS HCS messages.

Profiling reveals the new monitor has higher memory footprint, which causes more frequent GC pause, higher CPU usage, thus lower performance.

Actual Behavior

Expected Behavior
The new monitor with SDK v2 should perform as well as or better than old versions.

Environment:

Additional Context