Further to a previous post I have a five minute timeline with ten cameras (running fine by the way in proxy on a two year old iMac with Yosemite Beta 2) but I've got the backups bug. Every two seconds to be precise so I have disabled backups reluctantly.
It must be a bug. It would be quite nice to be in control of how often it made a backup.
No, you can't. And when running beta software, bugs are to be expected as well as it not being possible to pinpoint whether it's even FCP's fault. If you actually want to help, I would report it to both teams.