If you just want the magnitude, then a frequency swept source and oscilloscope is the easiest "fast" way. Otherwise an AC voltmeter, signal source, and pencil and paper like CatalinaWOW suggests works.
I almost always want phase as well so I use one of my manual function generators and my DSO with automatic phase and amplitude measurement to make the measurements while graphing the points of interest with pencil and paper. If you have a DSO which supports differentiation and FFTs which display both phase and magnitude, then you can do this in real time with a step function input and none of that time wasting swept sine nonsense.