Very slow backup

something happend with my database, it’s works very slow without load.
I have bucket with only 600 documents. this bucket configured for 700 MB using and currently uses only 35 MB. when I trying backup this bucket it’s required a lot of time ~5 minutes. this is really bad result because I have bucket with millions documents and backup will be unreal. Also I have problem with selecting data from database - all selection via View required a lot of time and very often I getting timeout excecption.
server not under loading, only 1-4% CPU usages and writting ~10 document per seconds.

I need some help.

Could you give me a little more details about the configuration? What version of Couchbase Server are you running? What kind of views are running? Are you using 1 node only in your development environment? How do you write to the server (which SDK etc.). I would love to help you on that.