I have been discovering that Calibre's
ebook-convert runs painfully slow converting HTML + cover image to ePub with a >1M input. Pandoc also seemed slow.
What, if anything, can I do to run things faster? Is there any way I can get (or get instructions to build) a template which could have the HTML and cover dropped in?
The impression I got from Wikipedia is that it's a relatively straightforward format, but I wanted to check in if there's something else already built that I should consider.