Fill Factor Setting and Performance
The default fill factor is zero, which is identical to 100. As per the product documentation,


  The fill-factor value is a percentage from 1 to 100, and the
  server-wide default is 0 which means that the leaf-level pages are
  filled to capacity.


Trying to find an opitmal value for fill factor is a well-researched problem. In the described scenario, there is not much to be done unless the table doesn't use default values.