I have some bad news.
Since Lord Tirian told me how I can see how much triangles a model has, I had a look at how many polygons the graphics currently in Planetfall use. And I discovered a lot of the graphics have much more polygons than I'd expect from glancing at the wireframe of the model. This includes ALL of woodelf's graphics.
If I understand correctly from previous cases, a model can be converted to a nif in an inefficient manner which creates lots of triangles. But when converted right, the nif can have much less triangles without any loss of quality at all.
The good news is that if these models were processed correctly, Planetfall would probably run much smoother, less lag when scrolling over the map etc. So I'm wondering if it's possible to process the existing nifs to reduce their polygon count. Or is that impossible without the source file before it got converted to nif?

I realize fixing old stuff is probably much more boring than creating models for new stuff, but doing it would improve Planetfall a lot.
Lord Tirian (or anyone else), interested in taking a look at what can be done?
These are the things that stood out to me during my review of the files in the Pak0.fpk:
Some stuff I put between brackets because at first glance their # of triangles seems to match the model's complexity. But because they were made by the same author who made extremely high polygon models, I assume my first glance could be wrong, and their poly count could be significantly reduced as well.
Stuff from woodelf:
Buildings:
Academy
(Alpha Prime)
Atmospheric Processor
Hologram Theatre
Sea Base/Pressure Dome
Sea Wall (currently found in the 'test facility' folder)
Temple of Planet
Biology Lab
Arrival Era Headquarters/Landing Pods: the legs are complex, but 10000+ polygons???
Cloning Vats
(Energy Bank)
Fission/Unity Reactor (same stuff in both folders)
Maintenance Bay
Network Node
This list is not complete. There are a couple other simple buildings as well, with still a higher than expected poly count. But because the model is so simple the poly count still only is 100 or so. Eg the rec commons, rec tanks...
Citysets:
caretakers_cityset.nif
spartans_cityset.nif
believers_cityset.nif
Improvements:
(Field Lab)
Landworked
(Tidal Harness)
Units:
(Foil)
(Needlejet)
Rover (a model by keldath which uses woodelf's rover as base)
Unity Rover (in the 'Tank' folder)
Transport Foil
Unity Foil
Stuff from other creators, or the creators are unknown to me because GeoModder found the model
Buildings:
- Aerospace Complex: As far as I can tell, this model may have a normal amount of triangles for how detailed it is, but I don't think it *needs* to be as detailed. For instance there are lots of half-spheres made of many sides (=faces?). At the scale these buildings are displayed in-game, these spheres could be made of much less faces and you wouldn't notice the difference.
- Antimatter Reactor: Scene Viewer crashes when I try to open this one. Can someone tell me how much triangles this one has?
- (Energy Nexus)
- Nuclear Reactor
- (Observation Bay)
- (Subsea Trunkline)
- Supercollider
Improvements:
- Solar Collector: Scene Viewer crashes when I try to open this one. Can someone tell me how much triangles this one has?
- Unity Pod
Resources
- Alien Artifact: 5000+ polygons! By The_Reckoning.
Units
- Sea Colony Pod: The_Reckoning
- Unity Supplies: The_Reckoning
- Supply Crawler: err, don't remember the author - could be The_Reckoning as well
Planetfall also includes a couple buildings which AFAIK come from Empire Earth 2. They have many triangles, but they are also more detailed than the average civ4 building, so perhaps that poly count is normal. Still judging from The_Coyote's unit conversion it seems possible to seriously reduce polycount with hardly any negative effect on the looks. Perhaps the same is possible with these buildings? For instance it's pointless to keep those small windows in the Military Academy. Might as well remove them and add some black rectangles for windows to the dds texture instead. The models are:
- hydroplant.nif
- Skunkworks
- Assembly Hall
- Military Academy