This the sort of thing that is so vague and involves so many factors, it would be difficult to solve without actual testing.

• - You're on a 64 bit OS using a 64 bit version of Maya
• - Your firewall isn't hindering Maya
• - Your machine isn't overheating in any way
• - There isn't some crazy high sampling setting in your render settings, lights, shaders etc
• - You've went to Render>Batch Render>Options
  • - unchecked "Auto render threads" and set number of threads(it's weird, it seems to work better if manually specified)
  • - unchecked auto memory limit and set a manual limit
  • - tried checking on both "render on local machine" and "render on network machine"