That may be true, but all of takatos (beautiful) weapons have a really high polycount and there has never been a problem with them, so it seems like it doesn't really matter.
Your work is quite impressive too. What program do you use? MS3D?
Regarding the CX-32, I have a custom flat-shaded version of it, and I've never gotten lag from it. Interestingly enough that was actually a little contest between GC and I to see who could make the best gun.
But onto my point; most of my models do in fact use selective smoothing on certain parts (especially my swords) so I doubt it's the smooth shading, and I can spawn 7 of each uber weapon (9 weapons at ~6k polygons a pop) without dying from latency poisoning. The only mesh lag I've ever gotten was when I exported a 500k+ stock model as a playertype to test Torque's limits. Perhaps it's just your system?