The desired speed performance for one or more nodes in your design. You can specify timing requirements for t_SU, t_H, t_CO, t_PD, and f_MAX. You can specify timing requirements for the entire project or for individual clock signals in your design in the Clocks page of the Settings dialog box (Assignments menu). Alternatively, you can make timing assignments, including assignments for timing requirements, to individual entities, nodes, and pins with the Assignment Organizer command (Assignments menu).

When you specify project-wide or individual timing requirements and use timing-driven compilation, the Fitter optimizes the placement of logic in the device to attempt to achieve the specified timing goals. After compilation, the Compilation Report shows whether the specified timing requirements were achieved.