High CPU when using InfluxDB for load testing metrics storage

I’m using InfluxDB to store my JMeter metrics when load test is running. I send these metrics via Backend Listener
Then it collected in Influx database and is sent to Grafana.
On low load level everything is fine, but when it comes to somewhat near 2-2.5 thousands of transactions per second CPU reach more than 90% and all of this is consumed by influxdb.

The number of cores was increased from 4 to 10, but it didn’t really affect performance. Reducing the number of JMeter’s java threads from 600 to 250 somewhat helps, not for long.
Is there some tips for me on how to optimise cpu usage by InfluxDB?