I think this goes back to shading issues. For me personally I have a 3 ghz and a crappy ass graphics card. When it's up at Shader 2 it's laggy as hell but when it's down on shader one it's just fine. There are some noticeable graphics differences but that's life.

I like the new demo better for a couple of reasons. One the menus are better, secondly I can choose a few combat options now where as every single button was grey in demo one (like fire at will and skirmish.)

The Aztecs are a nice challenge. Not easy in the least means and the old CTRL-A charge does not work against them. In last battle even with groups, and movement and flanking it was rough I think i ended without about 6-8 guys.