A lot depends on where you are, what ship you are in, what kind of station you are in.
Some ships hit performance a bit. Biggest ship I've had is a Lakon 6 and it was the worst performer or least sharing worst with the Cobra. Sidies are ok as are Eagles and Vipers, Haulers are somewhere in in the middle.
Some stations hit performance more than others do. The more complex the worse the performance.
Where you are also makes a difference. Station entrances seem the worst in my experience.
Running the game well in deep space with certain ships is one thing, trying to get a minimum 75fps all the time (which is what you want) is another thing entirely even with high end hardware.
Hopefully performance will improve as time goes on with help from FD, OVR and the GPU companies.
Of course you're right - to have at least some minor level of reproducibility and eliminate factors as varying cockpit geometry and more complex geometry being more or less obscured by them, all my benchmarks were measures of docking and undocking in the tutorial, doing roughly the same and measuring for a predefined timeframe.
I'll probably test a little more with different ships and situations, but so far, I haven't noticed any major drops in beta 2.x (currently in a Cobra).