Can't open big PDFs

[RubarMo]

Hello there,
Thanks a lot for this great app. I have a problem wuth importing big pdf files. it takes a lot of time and if not freezed the scrolling is not smooth. and when i sync the app between different platforms, the backuped files in files explorer is enormously big. my 500 pages pdf is about 50 Megabyte, and the backup folder contains 500 files, 50 Megabyte each. so the backup folder is about 25 Gigabyte. and the sync (Upload and Download) is veeery slow. If you could solve this problem it will be best note taking app on the internet.
Than you again.