hammer uses all available ressources for the compile, vbsp-vvis-vrad run on normal priority and hence slow down the system. the hammer app itself then misses its intervals to send lifesigns to windows, hence getting the "not responding". unfortunately this way it´s hard to know if it crashed or is still working. open the taskmanager and see if vbsp-vvis-vrad is using any CPU, if not, something went wrong and the compile crashed.
If it doesn´t crash in your case, there might be something wrong with you map, and using VBCT won´t help.
VBCT is basically just an advanced and more relyable gui for the same processes, but runs them on a lower system priority and gives you the precious info if it´s still compiling or if crashed.
From personal experience, sometimes hammercompile bugs out, sometimes vbct, so i tend to switch.