Why should you register SharePoint Framework extensions programmatically and did you know that you can deploy your solution to SharePoint directly from npm?
Office 365 CDN can help you improve performance of SharePoint Framework solutions. But if you configure it incorrectly, your solutions won't work at all.
Using the Office 365 CDN, you can optimize serving static assets to your users. While this capability is disabled by default, you can easily enable and manage it using the Office 365 CLI.