How to configure Solr to require less memory?

Question

Solr

Hello.
Uploaded 800 million lines to Solr (from 1 to 10 words, line length up to 100 characters). I tried to make SOLR_JAVA_MEM 4Gb - Java crashes with an OutOfMemory error after a couple of requests to the solar. I increased it to 24 Gb - it works OK, but still sometimes it gets to 20 Gb and I am tormented by doubts that with an increase in the load on the solar, this threshold can also be passed.
Actually, the question is: how to configure Solr so that it eats less memory?
Thank you.