Well, it does mean a bit more battery drain to do the pagination on the Reader rather than the PC, but I'd say the time
waiting for it to finish would be the bigger deal to me (and not that big a deal).
Folks have been using Calibre in its various incarnations for several years, and to my recollection no one has ever so much as hinted that they saw any noticeable battery effect from it, so I think you're probably safe enough.
