WRS means Web Rendering Service, which Google bot uses to render pages like a browser, so that we can find everything in the same method that users see.
Crawl budget is the system that we use to hinder the number of requests that we send to server, so we can not cause issues during our crawling. This is not something that most sites need to worry about since Google has no any difficulty in crawling enough URLs from the websites.
Well there is no any specific threshold, Crawl budget topic that mostly big websites for example, websites with more than a few 1,00,000 URLs must have to think. For crawl budgeting, our systems automatically determine the maximum number of requests that a server can process over a given period of time. This is done automatically and adjusted over time.
As we see that the server starts to reduce down or return server bugs, we reduces the crawl budget available to our crawlers.
We use plenty of caching to lessen the number of requests needed to render a page. However, in most of the cases, rendering results in more than just one request, so more than HTML file being made to the server.
However, in brief if you working on a large site, then lessen the number of embedded resources needed to render a page can help with crawling. Doing this generally also makes pages boosted for users as well. So you can cover both of the sides at while time.