The rise of science produced a major change in attitude.
It became clear that there had been significant changes in the Earth's topography over time and that these changes could neither be accounted for by natural processes operating during the brief nor by the postulated Noachian flood.
Ussher accepted the Biblical account at face value, relying on the Biblical genealogies and on extant historical records.
He implicitly assumed that the world was created much as it is now.
LAME, the open source audio encoder, is a good example of a single-threaded application.
It will never use more than one thread (so when I'm encoding MP3 files, I just run four or more copies at the same time, each encoding a list of audio files).