HitCounter is an extension to create top-X lists of entries or pages in your site. It keeps track of hits for the last_week and for last_month.
Hitcounter requires a modern PivotX (version 2 and up) and a SQL database.
It has a limited design scope, meaning it's meant for creating top lists. It's not a generic PivotX statistics tool.
It has been build for speed. Updating statistics costs 1 query per hit. Updating a 'list total' happens every scheduler-run and only updates values that have changed.