What you experience is perfectly normal, Screen Space Ambient Occlusion basically makes it so that every frame
has to be rendered twice, so anything around 50% of performance drop can be expected. And the very high
texture/graphics-slider setting doesn't make things more fluid either.
This is actually an interesting topic in general, because there are some common misconceptions about games,
graphics performance and the hardware requirements connected to it. In fast moving games like FPS you need a
much lower graphic fidelity to make things look good: lower resolution textures, less polygons, etc. In a rather
static game like Automation you need very high fidelity stuff to make it look good, as the player studies details
much more frequently. So what does take more performance then? The GFX card does not really care if stuff
moves or not... so yes, a game like Automation is actually more taxing in that regard.
Sure, the engine could probably be optimized by a hundred Crytek employees to squeeze out some x% additional
performance... but that still wouldn't solve the high requirements "problem". I put quotes on that because being
able to run at the highest setting can hardly be considered a problem.
We have put in higher fidelity options
in order to make the game "future proof" - this does not mean you have to be able to run it on those settings
with a machine of today.
I would suggest you keep SSAO turned off for the moment, the PC that can handle that without an issue is
probably somewhere in the $3000 price region for now.