Been playing with REAGL/REGAL waveform (see #550 and others), that seems supported on my Kobo Glo HD, and probably is on other recent Kobo.
It's a bit different from the usual partial refresh (a bit faster, a bit ugly as letters morph into the next ones:), so I'm not sure it's really interesting (and may be it just feels faster because the morphing is happening quickly).
Anyway, it's the default mode on Kindles.

There are some occasions where it is really worse, which could be solved by using a "ui" refresh instead of the default "partial" refresh.
I wonder if it's the same on kindle, so could Kindle users check and tell me how the following behave on their device:

Dict lookup, multiple result: when using >> to see next result:
1a) only the title and definition texts are updated, the dict window stays and is not redrawn
1b) it feels like the dict windows is closed and a new one redrawn (because borders are refreshed, and morph into white)

Wikipedia Save as epub, when downloading images:
2a) Only the numbers 4 / 19 feels updated in a single InfoMessage
2b) It looks like the InfoMessage is closed and a new one shown for earch Fetching Image 4 / 19...

I get 1a) and 2a) on my Kobo with default refresh, but 1b) and 2b) when I use REGAL waveform.
What do you get on Kindle ?

(If you get 1b or 2b, there are some work to be done - otherwise, I won't bother "fixing" REGAL on Kobo).

Oh, and:
3) do you get a double full refresh when opeining a book ?