Although search engines are nowadays able to render web pages, it's not a best practice to actually rely on that if you want to rank well in the organic results. Instead, make sure to user server-side rendering or pre-render your webpages with a service like prerender.io. If you want to know why, then keep on reading.
Rendering pages costs a lot of server resources, so search engines can only allocate a small amount of its resources to rendering web pages. This means you shouldn't be surprised it can take search engines several days, or even weeks, to index your freshly published content. For comparison: with little effort you can have regular HTML pages indexed in a few hours.
It's important to have you content indexed quickly because if search engines haven't indexed your content, it won't rank. Until your content is indexed, you'll get zero traffic from it.
And when you're making updates to the content over time, again it'll take search engines time to process those changes.
On top of that, links to other content won't be crawled either until search engines have rendered your page. Only then they'll be able to learn about those links, and queue them for crawling. And guess what? Search engines will crawl the content that's linked and again find that it requires rendering by the indexing process so it's passed on to the indexer.
As you can see, this is a very slow and inefficient process. And as a result of this, it hurts your SEO performance.