StTraft

maybe you can try my fix on this. I've encountered the same issue as you before. [prevent from undefined value for deltaX and deltaY](https://github.com/souhe/reactScrollbar/pull/37/commits/56f3a9d65e8c48f4758be9de1a22961468161912)

Actually I have found using PureRenderMixin on the content wrapping Component can help. It may cause by, as @tkh44 said, layout thrashing. But I suspect more on updating each element...