For the grass you say, "I drew every blade." Maybe for that try a brush stroke instead of individual vector blades. If there is no suitable preset brush for grass you can make one. I think they are simply png files with a transparent background.
Did you draw the motorcycle in Anime Studio? or import it from another program? Is that bike chain rigged to animate? or will it just be static?
As people said above, try drawing things in a bitmap program; Photoshop or GIMP or the like and importing the png files.
Simplify your vector drawings. Delete any unnecessary points or shapes. You can usually select every other point and delete it, unless the point is at a crucial corner, or the shape is very complex. As someone else in another thread pointed out, small repeating objects can me made as one "shape" in Anime Studio, which should reduce memory usage.
That grass could easily be a bitmapped texture. Don't try to put too much detail where it isn't needed. We can't discern each blade of grass.
In that building, it looks as if you've made each window out of many rectangles. Simplify this. Make them out of fewer rectangles.
