You are going to have to be much much more specific.
What kind of video are you trying to stream? 1080p, 720p, dvd quality, youtube?? those are very different factors.
Is this on a windows device or a different device.
A modern celeron or pentium wiht 4gb of ram is enough to stream 1080p over a wired network. Now if using wifi then the wifi network will have as much to do with the performance as the computer itself.