In reply to Virginia Wilson.

Because this is a security update, you should absolutely update as soon as possible.

As for caching, I would recommend clearing your cache after updating. It is probably unnecessary, but it wouldn't hurt. You can always check with your caching plugin author for their advice.

The update shouldn't affect any plugins that are already running fine on 5.4, but if you're worried about that, you should ask your web host about setting up a staging site for you to test the update on, which is basically just a duplicate of your real (production) site.