> GMail is fast. All the time. No matter how much mail you have. That's because it runs from a local database and all server interaction is abstracted behind sync and local accesses to data.

I don't know about Android, but on iOS, the Gmail app is much slower to launch and navigate than the stock mail app. I think that, on launch, the Gmail app makes some requests before showing you any of even your locally cached data, which always struck me as poor design.