Posted 14 January 2015 - 02:20 PM
A free alternative (for smaller amounts of data) would be to manually backup files to google drive via the web browser interface when you are logged into gmail. If a file is private you would need to place it in an encrypted zip or 7z archive before upload. Files uploaded in this way will be safe from attack unless you have some sort of "sync"ed backup system which automaticvally updates the backups within google drive. You could also make this kind of upload to other email providers which let you store large attachments, or to other online backup and file hosting services, as long as it's a matter of "open browser-->visit site-->log in-->upload files-->log out-->close browser-->clear history,cookies and temp files" then the uploaded files should be safe.
Your mention of online backup services being agonizingly slow might be due to poor upload speeds on your connection (if it happens with all sites you try and upload files to), in this case you might think about backing up to cd or dvd discs, some of these are non-rewritable so couln't be edited by malware very easily, but you can't get much data on a cd or dvd disc so you would likely go through them rather fast.
Back on this site, for a while anyway, been so busy the last year.
My systems:2 laptops, intel i3 processors, windows 8.1 installed on the hard-drive and linux mint 17.3 MATE installed to USB