If you have unconditional breakpoints and visualizations such as anlogs/digital etc then the arduino might be producing messages faster than the pc can process them. 

In this case alter the project "Thottle (ms)" property to 100 (or a higher value depending on the speed of your computer. The correct value will enable your pc to keep up with the arduino and stay "realt-time"

The default throttle in 1210.24 is 80 milliseconds, preventing the arduino from executing a breakpoint within 80 milliseconds of another. 

Normally, with conditional or well placed breakpoints the speed of the arduino will not be affected by the throttle delay. 

The throttle setting is more useful for new users and quick project tests. It can be disabled entirely by settting "Throttle Enabled = False". The default is True.