Two jobs that make a national dataset usable: drop the vertex count until the file is web-sized, and cut it down to the area you actually work in.
{{ srcCrsNote }}
{{ notice }}
{{ simplifyPreview }}
{{ maskNote }}
Nothing read yet. Simplification works on lines and polygons; points pass through untouched.
Clipping here is a selection, not a geometry cut: a feature is kept whole when its point — or its centroid, for lines and polygons — falls inside the mask or rectangle. RICE says so rather than implying a true intersection.