Yep, we have an SPA at work. It's not even small - around 2MB - but it loads, parses, and renders almost instantly (say <300ms - not bad for a complex app). However, in practice users don't get into the app for a couple of seconds. This is due to it making several slow network requests to check auth and load data before letting you in.

I have a WIP branch that caches things locally, but my boss tells me that the app is fast enough and I should be working on other things. And I'm loathe to sneak it in without proper testing as caching is something that has a tendency to break in horrible ways if you're not careful.