It is updated roughly every 5 minutes, that’s actually really good for a feed reader.
RSS is never real time. Feed readers have to fetch the feed repeatedly to pick up changes. Doing so far more often than there are updates would be a waste of bandwidth and in many cases the server hosting the feed would tell the fetcher to back off or outright block it.
If you need the content quicker you can use a local feed reading app where the app is doing the fetching rather than the server as is the case with Newsblur. They may allow you to fetch even more often.