The first thing, is that you shouldn't need to optimize a fresh copy of Windows. Did you Optimize the previous version of XP? If not, the optimization may be the issue. You should only optimize if you have problems.
Did you make any bios changes? I like to disable in the bios, any hardware devices that aren't being used, like sound, and extra drive channels, and unused ports.
Typically, when you need to increase the pulse width, it's due to a weak signal from the parallel port. There are probably numerous things that can cause this, and I really don't have an answer for you.
Did you install XP in Standard PC mode, or ACPI? What was it before?