Can you elaborate or create an issue on Github? I primarily use Firefox and haven't noticed anything.
We support OPDS for consumption, but not for consuming content. I have some loose plans to support upstream sites/sources, but nothing concrete nor planned.
If I can repro this more reliably, I'll definitely report. It's a very subtle flicker where the content appears to the left of where it should be when flipping through pages.
I've been a big fan of the Plex approach for curation.
Would be awesome to integrate some one-click addition from high-quality ebook sources like Standard Ebooks (does it support upstream OPDS sources?).