Split the pie into three pieces:

  1. Heavy Work
  2. Interface Logic and Trivial Work
  3. Interface Rendering

You want 1,2 to run on compute servers and 3 to run locally.

Some other people want 1 to run on compute servers and 2,3 to run locally.

I really don't think it matters where 2 runs as long as 1 is fast and 3 is responsive.