[Insight-users] Whats most expensive; the optimizer or the metric?

[motes motes]

I am trying to understand which of the components in the image
registration method is the most expensive. Now the optimizer is run
for each iteration where it starts the optimizer which runs through
all the pixels in the fixed image. Even though the optimizer hardly
makes any sense without a metric I would still say that the most
expensive operation is the computation done by the metric or am I
missing something here?