I've just started using SadMan Sudoku, and noticed that the CPU usage is sometimes very high. Why is this?

A. Sudoku is busy building up a library of puzzles. It does this in the background so that there's always a puzzle ready when you want one. Once the library is full, which may take several hours, it will stop. You can:

1. Leave it running unattended for a while to give it a chance to fill its library without the fan bothering you.
2. Disable background creation of puzzles. View -> Options -> Options tab -> Create puzzles in the background. But if the library is empty when you want a new puzzle, you'll have to wait while one is generated.
3. View some stats on the library to give you an idea how much longer it will be annoying you. View -> Library statistics. The library is set to hold 2700 puzzles, split across the various grades, works out at 300 puzzles per grade.

Note: this shouldn't happen from version 3.2 onwards (released 10 October 2008) as Sudoku is now installed with a pre-built library containing 2700 sudokus. As you play or print the sudokus, more are automatically created to replace them.