Performance issue when opening multiple buckets

I am wondering is there some guidelines how many buckets one can open without suffering major performance issues ?
I was able to open 2 buckets fine and don’t see any major delay when writing or reading docs. But once i add a 3 bucket it becomes major as far as delay goes for the 3 bucket. If i do a basic doc insert on the 3 bucket it takes up to 4 seconds for the insert to complete. I know its not the bucket because if i remove the 2 nd bucket the 3 bucket insert is again ms. So i am wondering what causes this giant jump in delay for insert and get’s ? As there a workaround or fix or just a fact that one should not open more then 2 buckets at a given time ?