ZedGraph does not appear to be supported by the original developers anymore. However, you can find it as part of other projects where updates have been made.
For example, per this discussion on a ZedGraph project discussion list:
So I highly optimized ZedGraph for all
the curves, and objects. Basically, I
optimized how it uses GDI and
specifically made it only draw objects
that will fit in the the chart.
So it scrolls and zooms now extremely
efficiently even if I have many
millions of objects on the chart. Plus
it users nearly zero CPU when it's
running in real time as slower speeds
for tracking financial charts.
I fixed a few defects also.
You can find a fork of the repo with the changes here.
