Yes, it was done for performance! This was obvious once you look at the tablet offerings Amazon has now, none of which are designed for anything more than consumption.
The tablet offerings they have now? Their tablets have never been designed to be anything other than an Amazon store client, which I wouldn't mind too much if the Amazon app store weren't such a wasteland.
I got one for the sole purpose of access to the amazon instance library for my daughter since it wasn't an android offering at the moment.
I tried to use it as an android tablet, I was able to come up with most of the apps needed but in the end it was little things like lack of configuration that just made it useless to me. Not being able to change the keyboard and such.
Now it's only used by my daughter for content and solarium mobile.