… how I can build a compiled application interface …
Unlike browser-based applications, executables have to be compiled for (and deployed to and tested on) each target operating system. That’s no small job. If you really want to spend the rest of your career fire-fighting the latest Microsoft update that’s broken your favourite Windows UI widget, Good Luck.
At least writing browser-based applications, you’re working ion a more insulated world (although not entirely without its own “challenges”).
… to increase both speed and security …
What makes you think a compiled application will be any more secure that what you have now?
OK, people can’t look at the HTML source code, but what does that matter? There shouldn’t be anything “sensitive” held at the client end anyway. You should regard it as completely untrustworthy. That’s why we have TLS, server-side validation and authentication and all those other, Good Things that we jealously guard on our servers.
What makes you think it will be any faster than what you have already?
By far the slowest operation in all this will be pushing the request to the server and waiting for the response. Just making the client application go (a tiny) bit faster is not going to make any major inroads into that.