Right - after having a good fiddle with descr_model_battle.txt I think I've got it sorted. For the sake of posterity, it was as simple as using notepad to find & replace the numbers at each and every reference to sprites & set it a bit higher. I'm assuming they're set in metres.


In any case, changing them from 60.0 or 100.0 to 200.0 vastly increased the distance at which 3d models are displayed but still meant that the 2d models are used at large distances which in turn is much less hardware intensive. For example, providing the enemy army doesn't start right beside you - at the beginning of the battle, all, or at least most of, my troops were in clearly visible 3d while the enemy army were clearly visible as 2d. This gave me just less than double the fps of rendering ALL the 3d models on the screen at one time - which is a massive improvement!

At a distance of 200 metres the models look very small so the transition between 2d and 3d, imo anyway, is much better than panning along your line at ground level and physically seeing the models going from 2d to 3d right before your eyes which is what the 'high' model detail preset does - at least using BI.exe anyway.