On Saturday, January 12, 2013 2:10:58 PM UTC-8, Existential Angst wrote:

In a portable generator.
Does one type of load vs the other make it more difficult for a typical
portable generator to maintain constant voltage?

Yes, of course. The arc-generation of a welder (and its
internal control switches) is a very difficult load, even
for a full electric power grid let alone a small generator.
This is because the so-called 'power factor' is indeterminate.

Computer power supplies are also somewhat troublesome
(but for a different reason: they respond to brown-out
by increasing their current demands).

The most reliable way to drive a welder from a generator, is to buy a
welder that's gas-powered.