dima777,
1) The money traded through excel is with heavily extended versions (i.e. plug-ins).
2) The problem is not VBA, it's that excel was not built for either internet connectivity nor rapid refreshing.
Regards,
Max Dama
dima777,
Here's a simple visual explanation:
The solid line in the bottom left chart (d) has been over-optimized so it is not robust (i.e. its future performance is not reliable because it wiggles around to much).
The solid line in (c) is robust although it is not perfecty...