Only compile what you need to. If you're just testing entities or layout, you don't need vis or lighting info, so just do VBSP and turn off VVIS and VRAD. If you're just doing a lighting test, you don't need proper visability info, just the basics that VVIS provides to VRAD, so do a fast VVIS (and if you don't need to do super fine tuning, just leave VRAD at fast too)
45 isn't bad for a full on release compile. If you're PC is getting on a little that's fine. Mine takes about 50 for snowplow and my PC was a BEAST, but it was a beast five years ago. (Frozen's newer rig takes 20)
You only know you have problems when VVIS specifically is taking most of the time, especially as if you're running VRAD for HDR every time, VRAD is running twice, and for local testing compiles you really don't need that.
Also, for things like leak checking, just run VBSP, don't bother with VVIS or VRAD since the error is in VBSP.
Look at your most recent compile log, scroll through and see what times VBSP,VVIS,VRAD and the second VRAD (if applicable) are taking. Then tell us. If VVIS is taking longer than VRAD, you might need to do some geometry optimisation. Otherwise I'd just say you've got an older PC and are compiling on full every time.
ninja edit: Also, hammer will stop responding during a compile, that is normal. Just leave it be unless you see VBSP.exe, VBSP.exe or VRAD.exe at 0%cpu, then they've crashed.