I often talk about automating the maintenance of a WordPress blog. I have one partner, very few employees, but run several web sites. I am not a security expert, so I put the onus of security on a managed WordPress hosting solution. Also, I let the same hosting package, albeit a little pricier than your $5/month GoDaddy or Bluehost package, handle speed. They take care of things like asset distribution (in terms of a content delivery network or CDN), caching, and custom server tweaks. They keep an eye on the code being run on their servers to make certain it is optimized for speed and efficiency. Underneath that, WordPress does a decent job on its own in terms of speed and security.
Even with how awesome WordPress is out of the box, and the extra perks you get with a managed WordPress host, I always felt like there was still one area that was somewhat of an issue, in terms of speed, and to a lesser degree, storage. Images.