High latency in first query to completion suggester

The first query to a completion suggester field after an indexation is taking several seconds to some minutes, whereas the following queries are in the tens of milliseconds (tested in Elastic 8.3).

I think this might be due to lazy loading of new FST segments into memory - is this possible?

If so, it is possible to make this loading eager, for example with the index.store.preload configuration? And which file extensions should be preloaded?
Preloading data into the file system cache | Elasticsearch Guide [8.3] | Elastic

Having a program periodically issue a query (e.g. every 10 seconds) resulted in much higher stability in the request latency, even while indexing is happening.

This seems like a valid use case for the index warmers, but unfortunately, they have been removed as of version 8.3.

Is there any alternative to having that periodic pinging? Should this be reported as an issue?