I do use the WP-cache plugin and it does help a little bit.

The UI enhancements have been great, however the change in database code is not backed up by performance data.

It would be interesting to know where exactly the performance tweaks have been done.

Regarding Autosave, I do accept that I generalized it a little bit, the absence of this feature was one of the reasons I shifted to a desktop based client

And don’t assume the autosave feature is only for those who write online. And don’t assume all regular bloggers use offsite or other tools for writing their material. I complained about this bitterly when repeatedly I lost what I was working on, written up elsewhere but doing last minute edit checks before posting via the WordPress Write Post panel. A slip of the backspace key sends the browser window back a page, losing what you’ve done. Thinking everything is fine and hitting Publish, only to have the system crash, Internet access go offline, or other problems can also lose post data. It only takes a second and your post is history.

So the autosave feature isn’t limited to online writers. It helps everyone, just in case things go bork in the post.