New firmware benefits for offline kindles?

[remember]

I don't connect my Kindles to Amazon servers. I've been using them the same way for 15 years - to read books and articles/newspapers.

What benefits are offered by the latest firmwares? I know there is, on paper, some changes - X-ray and changes in the UI. If other technology is an indication, newer firmware will be slower than the older ones. I'm inclined to run the oldest firmware released for a Kindle, or close to it.

Based on my reading, this would break compatibility with a lot of Kindle hacks. But for pure reading, it should run faster.

What do you think?