Use a single flat array for the visited vertices

Replace the array of Uint8Arrays, which was rebuilt with fill().map()
on every iteration, by one flat Uint8Array that is allocated once and
cleared at the start of each iteration.

binaries/data/mods/public/maps/random/rmgen/painter/SmoothingPainter.js

@@ -26,20 +26,23 @@ SmoothingPainter.prototype.paint = function(area)
 	const brushPoints = getPointsInBoundingBox(getBoundingBox(
 		new Array(2).fill(0).map((zero, i) => new Vector2D(1, 1).mult(this.size).mult(i ? 1 : -1))));
 
+	const vertexSize = g_Map.height.length;
+
+	// Additional complexity to process all 4 vertices of each tile, i.e the last row too
+	const seen = new Uint8Array(vertexSize * vertexSize);
+
 	for (let i = 0; i < this.iterations; ++i)
 	{
-		// Additional complexity to process all 4 vertices of each tile, i.e the last row too
-		const vertexSize = g_Map.height.length;
-		const seen = new Array(vertexSize).fill(0).map(zero => new Uint8Array(vertexSize).fill(0));
+		seen.fill(0);
 
 		for (const point of area.getPoints())
 			for (const tileVertex of g_TileVertices)
 			{
 				const vertex = Vector2D.add(point, tileVertex);
-				if (!g_Map.validHeight(vertex) || seen[vertex.x][vertex.y])
+				if (!g_Map.validHeight(vertex) || seen[vertex.x * vertexSize + vertex.y])
 					continue;
 
-				seen[vertex.x][vertex.y] = 1;
+				seen[vertex.x * vertexSize + vertex.y] = 1;
 
 				let sumWeightedHeights = 0;
 				let sumWeights = 0;