[tjader]

KOReader typesets the whole book at once. It is needed in order to get page counts right, for example.

[taeric]

Even if that is the case, it has to redo this how often? If the page counts are to be stable, I'm assuming so are page numbers? At which point we are back to this not being something I would expect to slow things down appreciably on the vast majority of actual uses.

Still, I should acknowledge you provided an example. It surprises me.

[tjader]

It needs to rerender everything whenever you change any setting that affects typesetting. This used to be quite annoying when trying out fonts or find the best value for some setting, but recently they implemented a better way so that it first renders the current fragment (usually a chapter), releases the UI so that you can read, and renders the rest in the background. Page counts and some other stuff are broken in this meantime.

[throwanem]

> it has to redo this how often?

As often as the font size changes.