Tesseract is nice, but not good enough that there is no opportunity for another, better solution.

You can achieve colour PDFs smaller than group4 binary compression of the same images. And 10x smaller than a Jpeg compressed PDF

I handle many scanned documents so my source data is typically a 300ppi image of a book/document/newspaper etc

> My preliminary speed tests were fairly slow on my MacBook. However, once I deployed the app to an actual iPhone the speed of OCR was extremely promising (possibly due to the Vision framework using the GPU).

I don't know a lot about the specifics of where (hardware-wise) this gets run, but I'd assume any semi-modern Mac would also have an accelerated compute for this kind of thing. Running it on a Mac Mini would ease my worries about battery and heat issues. I would've guessed that they'd scale better as well, but I have no idea if that's actually the case. Also, you'd be able to run the server as a service for automatic restarts and such.

All that said, a rack of iPhones is pretty fun.

This is specifically for historic documents that tesseract will handle poorly. It also provides a good interface for retraining models on a specific document set, which will help for documents that are different from the training set.