Answer:
Moving slowly.
Explanation:
The person that Scout is referring to has a lot of things on his mind and while contemplating, he starts walking slowly.
"I made perhaps one step a minute" is an obvious exaggeration to describe how slowly he was moving as a result of his conflicting thoughts.
He probably just received disturbing news about something and his brain is still trying to process it without much success, so with the turmoil in his head, he began to move slowly.
"With this thought in mind..." further proves he just received distressing news and is devastated to the point of "making one step a minute"
