Sharepoint Online vs file references

Hey folks,

I'm pretty much lost trying to use Sharepoint Online as CMS. "Regular" Sharepoint is about to get shut down in our company, and we're supposed to switch to SP Online instead.

Setting up the connection was straightforward enough, and I can checkout files with no problems. I'm facing two major issues though:

1. The most critical issue is that FrameMaker seemingly cannot save or load any file references. All our documents are organized in .book files, with images referenced from a sub folder of the respective book. So we literally have thousands of files references (across ~200 book files). All of these break whenever we try to use SP Online.

2. Another issue access speed is excrutiatingly slow. Larger files take forever to load and open, and even a simple .book file will only down- or upload after a brief pause, followed by FrameMaker's placeholder "progress" bar, and another brief pause. This happens everytime and on any connection, even Gb fibre optic LAN.

Is there any way to use SP Online with working file references, and maybe to speed things up a little? Maybe some tweak in the SharePoint backend? Thanks in advance!

Cheers,
Alex