Not alone! I am using the developer version, and it's a shame because I have found it way easier to create widgets using react and typescript + with experience builder we get to use the new 4.x javascript SDK. I can create new functionality for my team in a just a day in experience builder. Always takes me longer in WAB.
But these performance issues are a real drag. When I called them about this a year ago, they just said I should remove the larger layers from the application. Obviously, this is not a solution when our workflows depend on those layers entirely.