Create 1M items and send 6 values for each item using Zabbix sender, remove code that inserts history into database.

Observe that can only insert 353913 values/sec if receiving concurrently with Zabbix sender or 638993.7 if data is already in history queue:
3298455:20221027:165043.176 HISTORY SYNC: processed 6000000 in 9.389 (638993.7 values/sec)
3298459:20221027:165113.095 HISTORY SYNC: processed 6000000 in 16.953 (353913.7 values/sec)

Apply patch
simple_optimizations.diff

Notice speed improvement to 1538701.1 values/sec and 1.2m~ values/sec when inserting and receiving with Zabbix sender :

3249574:20221027:164803.720 HISTORY SYNC: processed 6000000 in 3.899 (1538701.1 values/sec)
3249581:20221027:164817.292 HISTORY SYNC: processed 625250 in 0.579 (1078126.4 values/sec)
3249573:20221027:164818.851 HISTORY SYNC: processed 742250 in 0.592 (1253323.4 values/sec)
3249575:20221027:164820.503 HISTORY SYNC: processed 811000 in 0.700 (1157581.2 values/sec)
3249581:20221027:164821.927 HISTORY SYNC: processed 699500 in 0.541 (1291600.2 values/sec)
3249580:20221027:164823.514 HISTORY SYNC: processed 768000 in 0.600 (1278066.9 values/sec)
3249573:20221027:164825.130 HISTORY SYNC: processed 780000 in 0.647 (1203796.5 values/sec)
3249582:20221027:164827.762 HISTORY SYNC: processed 1271500 in 1.650 (770389.6 values/sec)
3249573:20221027:164828.895 HISTORY SYNC: processed 302500 in 0.150 (2003382.1 values/sec)