modman,
the engine doesn't render many units that aren't visible GameCamera::computeVisibleQuads() still lies however, so there
are some units, tilesets, objects, etc. that are getting rendered that are indeed off screen. Omega actually gave me a the trig formulas for this a while back but I've yet to put them in, if you know C++ and the trig (or copy Omega's formulas from a posting back around March). Currently, it's not that far off, but it's ugly IMHO.
The reason you lag before a big attack is the path finder
that's on the list to be fixed. When a lot of units are moving, they are all using the path finder and it's inefficient. And finally, the water noise is annoying and needs to be fixed. All that needs to happen is that when a unit moves through water, see if they are in the visible quad (again, computed in GameCamera::computeVisibleQuads()) before deciding to play the water sound. As for the visuals, that sounds like a bug as well. Maybe you can enter a bug report? I might split it into two bugs, but one is fine for now.
I'll be back in town in a few days and will give the bug database, etc., more attention.
Also, on the lag issue, attempting to "can" the special effects caused by particle systems is pretty useless in a 3d world because some of the particles will be covered up by other 3d objects in the world. As wicow said, it does indeed sound like a CPU limitation. Regardless of which CPU you have, it shouldn't lag that hard it's a problem I'm actually hoping to address more in the future. I've actually made some performance optimizations on 0.2.11, but I intend on many more.
verarticus,
This problem is unrelated to the bugs modman pointed out. I actually took a quick stab at fixing this and broke the red circles on other things so I backed out the change. This is annoying because any time any unit issues a command with another unit as a target, a red circle appears, and it should only do that for orders that YOU issue yourself and not even for "auto-commands" (auto-repair, auto-attack, etc.)
thanks to both of you for reporting bugs!