ICD 4 Debugger Options - Clock
Set the option to use the fast internal RC clock for the selected device.
CLOCK OPTION CATEGORY
Use fast internal RC (FRC) in Debug mode (dsPIC®33F and PIC24F/H devices only) When debugging, use the device FRC for clocking instead of the oscillator specified for the application. This is useful when the application clock is slow. Checking this check box will let the application run at the slow speed but debug at the faster FRC speed. Reprogram after changing this setting.
Note: Peripherals that are not frozen will operate at the FRC speed while debugging.