"Training is slow" and "training is slow ON THE CPU with four million
parameters" are different problems with different fixes, and nothing in the log
told them apart — leaving it to be inferred from timings, which is how the
first guess at this went to the disk instead.
One line per run per value function, naming the device and the parameter count.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>