Another way to deal with redundancy like that is to add a couple more sheets with Edge Fade, Inner sheet effects on them and draw irregular patches of different grass textures on them.

You can convert the line to a polygon using 'Path to Poly' in the right click menu of the Fractalise tool. It looks like you might have a line width greater than zero, which will form an open polygon. Use Change properties to set the line to zero width and pick your fill, sheet, and layer.

I think Wyvern has the answer above. Draw the forest in smaller patches and increase the scale of the bitmap fill. You do that by opening the Fill Style Properties dialog (click the status bar where you see "FS:...."), pick the Bitmap Files tab, then find the fill you want to scale up in the dropdown box. The scale in the hieght and width boxes is in map units, whether that happens to be feet or metres.

Don't scale the fills up too much or you will end up with pixelation, which is where the fill shows it's pixels as squares.

There is a pink glow on the SYMBOLS CLIFF sheet. I've hidden it in this screen shot.

The main thing that slows CC3 down is the number of nodes, whether that is in an enormously intricate coastline, or a highly precises vector drawing of a tree used lots of times over the map.

The alternative to using lots of vector symbols is to create a png bitmap symbol of the same thing and use that instead.