Hi, Rob. 
I recently received an email from Wix regarding the transition to the MPA architecture, so I was aware that Wix would be moving toward a full MPA setup. Since participating in this topic earlier, I’ve understood that the Wix Editor behaves more like an SPA, while the Wix Studio Editor behaves more like an MPA.
However, when I read the email, I couldn’t help but wonder—weren’t websites built with Wix Studio already functioning essentially as MPAs? Were they not truly MPAs in the full, technical sense until now? If you happen to have any insights or additional context on this point, I’d really appreciate it.
Also, regarding the query parameter mentioned in your reply that can be used to enforce MPA mode: from what I read in the documentation, it seems to be intended for testing purposes only, and not something meant for production use. Is my understanding correct?
As I interpret it, this means that once Wix fully transitions everything to MPA architecture in the near future, site performance—specifically, initial load time and in-site navigation speed—will automatically improve without requiring us to take any action. Is that the right way to understand it?
Finally, on a personal note: as I mentioned in a previous post, I’m one of those people who prefer to display manually optimized AVIF images on their sites, rather than relying on Wix’s automatic image conversion and delivery system. In recent months, I discovered that by overriding an image element defined in the editor UI via code—like in the example below—I can force Wix to load my manually converted, original AVIF image uploaded to the Media Manager.
$w.onReady(function () {
$("#image").src = "https://static.wixstatic.com/media/XXXXX~mv2.avif";
});
I’d like to know if this is indeed a proper and reliable method, whether there’s a better way to achieve this, and if this approach is likely to continue working in the future. Personally, unless Wix introduces an option to opt out of automatic image conversion, I believe this is the only viable way to do it. 
Some time ago, someone on this forum was talking about the same thing and said it couldn’t be done, so I believed that. 
But recently, I tried it myself and realized, “It actually works!”