I with it was only slow with 10+ scatter plots. I can't get past three.

Using scatter plots (points only) with seven thousand points, the speed is
so much worse than either 2002 or 2003 that it is completely unusable.

From a new spreadsheet with four columnar series (one for x, four for y)
with 7000 elements:

Charting one series as a scatter plot is slightly slower than 2003 (few
seconds)
Charting two series as a scatter plot is slower than 2003 (few more seconds)
Charting three series as a scatter plot is slower than 2003 (less than a
minute)
Charting four series as a scatter plot appears hung but does eventually work
if left overnight.

Even simply redrawing the screen with the four series chart has taken over
an hour so far and has not finished. It slowly draws the first three series
and then seems to freeze on the fourth. The application appears hung with
100% CPU.

In this state, it is not even possible to get the data recovery dialog and
requires a task kill to exit.