BGP ingestion in Beryllium is too slow

While ingesting 1 million one-prefix BGP update messages takse 2-3 minutes with Lithium snapshot [0], corresponding Beryllium snapshot manages to ingest only around 300000 messages in 5 minutes [1].

There is no obvious reason for Beryllium to be slow this much, so this performance regression is a Bug.

[0] https://jenkins.opendaylight.org/releng/view/bgpcep/job/bgpcep-csit-1node-periodic-bgp-ingest-only-stable-lithium/92/robot/bgpcep-bgp-ingest.txt/Singlepeer%20Prefixcount/Wait_For_Stable_Talking_Ipv4_Topology/
[1] https://jenkins.opendaylight.org/releng/view/bgpcep/job/bgpcep-csit-1node-periodic-bgp-ingest-only-beryllium/88/robot/report/log.html#s1-s2-t5-k2-k2-k7-k29-k1-k6