Large numbers are unintuitive. If we’re conservative and add only 1 millisecond of latency for the 3 AZ replication, on 410 million records that is about 4 and a half days of time if the client is not doing any batching.
TSBS did batch 100 metrics at a time, the max per request that Timestream allows. As we (and others) have suggested, this could easily be one of the reasons it's harder to ingest more quickly without significantly more threads. TimescaleDB (and other TSDB's) allow much higher batching values.
