The Preferences dialog box controls your delay and timing analysis preferences. If you are using Tcl, consult the Tcl Command Summary for a list of the commands related to preferences.
You may wish to prevent Timer from calculating delays when the tool starts. (By default, Timer estimates all potential clock frequencies, as well as the delays corresponding to the four primary sets (All Inputs to All Outputs, All Inputs to Registers, Registers to All Outputs, Registers to Registers) associated with the slowest clock when the tool opens.)
Preferences - Precalculate Delays Selected
To change your option for pre-calculating delays, from the File menu, choose Preferences and deselect Precalculate delays.