Comment by robocat
Are you sure PHP is the bottleneck?
The author writes that Clickhouse takes 0.1s for an example request: https://news.ycombinator.com/item?id=42666703
PHP would need to be adding 0.1s CPU time for processing the request for the PHP code to become the bottleneck. That seems unlikely.
That 0.1s is to write 4k rows to clickhouse, not per (log write) request.