Large Array Performance Optimization, Resource Costs

I'm interested in discovering how to optimize Elasticsearch. Requirements:

[1] Using an index that contains 100,000 documents.
[2] Each document contains 2 fields: "id", "my_array"
[3] MATCH a KEYWORD against the "myArray" field. "myArray" could have the following number of elements listed in the four scenarios given below, each containing a string no more than 30 chars.
A. 100
B. 1000
C. 10000
D. 100000

What kind of configuration would allow me to match a single string in the scenarios above in less than 250 milliseconds under a load of 50 concurrent requests?

I think someone asked a simpler version of this question previously, but the Elasticsearch employee who responded did not provide any meaningful information in their response, they just said be "reasonable".

https://discuss.elastic.co/t/your-post-in-what-are-the-limitations-of-array-size-in-elastic-search/146275

Your link didn't work for me. The response I saw was this: What are the limitations of array size in elastic search? - #2 by jpountz

If so it seemed a perfectly reasonable answer to me. i.e. don't create a single JSON document with an array of a million ID strings which have to be rewritten entirely each time there's any change to that set.

The workaround would be to break this doc up into smaller ones.