Change root solvers to not produce new arrays each time but fill a passed one that can be reused. Yields io impressive performance improvements.

src/path/Curve.js

@@ -309,15 +309,15 @@ var Curve = this.Curve = Base.extend(/** @lends Curve# */{
 		return Curve.getParameter(this.getValues(), point.x, point.y);
 	},
 
-	getCrossings: function(point, matrix) {
+	getCrossings: function(point, matrix, roots) {
 		// Implement the crossing number algorithm:
 		// http://en.wikipedia.org/wiki/Point_in_polygon
 		// Solve the y-axis cubic polynominal for point.y and count all
 		// solutions to the right of point.x as crossings.
 		var vals = this.getValues(matrix),
-			roots = Curve.solveCubic(vals, 1, point.y),
+			num = Curve.solveCubic(vals, 1, point.y, roots),
 			crossings = 0;
-		for (var i = 0, l = roots != Infinity && roots.length; i < l; i++) {
+		for (var i = 0; i < num; i++) {
 			var t = roots[i];
 			if (t >= 0 && t < 1 && Curve.evaluate(vals, t, 0).x > point.x) {
 				// If we're close to 0 and are not changing y-direction from the
@@ -470,7 +470,7 @@ var Curve = this.Curve = Base.extend(/** @lends Curve# */{
 
 		// Converts from the point coordinates (p1, c1, c2, p2) for one axis to
 		// the polynomial coefficients and solves the polynomial for val
-		solveCubic: function (v, coord, val) {
+		solveCubic: function (v, coord, val, roots) {
 			var p1 = v[coord],
 				c1 = v[coord + 2],
 				c2 = v[coord + 4],
@@ -478,14 +478,15 @@ var Curve = this.Curve = Base.extend(/** @lends Curve# */{
 				c = 3 * (c1 - p1),
 				b = 3 * (c2 - c1) - c,
 				a = p2 - p1 - c - b;
-			return Numerical.solveCubic(a, b, c, p1 - val, Numerical.TOLERANCE);
+			return Numerical.solveCubic(a, b, c, p1 - val, roots,
+					Numerical.TOLERANCE);
 		},
 
 		getParameter: function(v, x, y) {
-			var txs = Curve.solveCubic(v, 0, x),
+			var txs = [],
-				tys = Curve.solveCubic(v, 1, y),
+				tys = [],
-				sx = txs === Infinity ? -1 : txs.length,
+				sx = Curve.solveCubic(v, 0, x, txs),
-				sy = tys === Infinity ? -1 : tys.length,
+				sy = Curve.solveCubic(v, 1, y, tys),
 				tx, ty;
 			// sx, sy == -1 means infinite solutions:
 			// Loop through all solutions for x and match with solutions for y,

src/path/Path.js

@@ -1191,9 +1191,11 @@ var Path = this.Path = PathItem.extend(/** @lends Path# */{
 		// number, meaning the starting point is inside the shape.
 		// http://en.wikipedia.org/wiki/Point_in_polygon
 		var curves = this.getCurves(),
-			crossings = 0;
+			crossings = 0,
+			// Reuse one array for root-finding, give garbage collector a break
+			roots = [];
 		for (var i = 0, l = curves.length; i < l; i++)
-			crossings += curves[i].getCrossings(point, matrix);
+			crossings += curves[i].getCrossings(point, matrix, roots);
 		return (crossings & 1) == 1;
 	},
 

src/util/Numerical.js

@@ -117,32 +117,34 @@ var Numerical = new function() {
 		 *
 		 * a*x^2 + b*x + c = 0
 		 */
-		solveQuadratic: function(a, b, c, tolerance) {
+		solveQuadratic: function(a, b, c, roots, tolerance) {
 			// After Numerical Recipes in C, 2nd edition, Press et al.,
 			// 5.6, Quadratic and Cubic Equations
 			// If problem is actually linear, return 0 or 1 easy roots
 			if (abs(a) < tolerance) {
-				if (abs(b) >= tolerance)
+				if (abs(b) >= tolerance) {
-					return [ -c / b ];
+					roots[0] = -c / b;
+					return 1;
+				}
 				// If all the coefficients are 0, infinite values are
 				// possible!
 				if (abs(c) < tolerance)
-					return Infinity; // Infinite solutions
+					return -1; // Infinite solutions
-				return []; // 0 solutions
+				return 0; // 0 solutions
 			}
 			var q = b * b - 4 * a * c;
 			if (q < 0)
-				return []; // 0 solutions
+				return 0; // 0 solutions
 			q = sqrt(q);
 			if (b < 0)
 				q = -q;
 			q = (b + q) * -0.5;
-			var roots = [];
+			var n = 0;
 			if (abs(q) >= tolerance)
-				roots.push(c / q);
+				roots[n++] = c / q;
 			if (abs(a) >= tolerance)
-				roots.push(q / a);
+				roots[n++] = q / a;
-			return roots; // 0, 1 or 2 solutions
+			return n; // 0, 1 or 2 solutions
 		},
 
 		/**
@@ -151,11 +153,11 @@ var Numerical = new function() {
 		 *
 		 * a*x^3 + b*x^2 + c*x + d = 0
 		 */
-	    solveCubic: function(a, b, c, d, tolerance) {
+	    solveCubic: function(a, b, c, d, roots, tolerance) {
 			// After Numerical Recipes in C, 2nd edition, Press et al.,
 			// 5.6, Quadratic and Cubic Equations
 			if (abs(a) < tolerance)
-			    return Numerical.solveQuadratic(b, c, d, tolerance);
+			    return Numerical.solveQuadratic(b, c, d, roots, tolerance);
 			// Normalize
 			b /= a;
 			c /= a;
@@ -173,18 +175,18 @@ var Numerical = new function() {
 				var theta = Math.acos(R / sqrt(Q3)),
 					// This sqrt is safe, since Q3 >= 0, and thus Q >= 0
 					q = -2 * sqrt(Q);
-				return [
+				roots[0] = q * cos(theta / 3) - b;
-					q * cos(theta / 3) - b,
+				roots[1] = q * cos((theta + 2 * PI) / 3) - b;
-					q * cos((theta + 2 * PI) / 3) - b,
+				roots[2] = q * cos((theta - 2 * PI) / 3) - b;
-					q * cos((theta - 2 * PI) / 3) - b
+				return 3;
-				];
 			} else { // One real root
 				var A = -Math.pow(abs(R) + sqrt(R2 - Q3), 1 / 3);
 				if (R < 0) A = -A;
 				var B = (abs(A) < tolerance) ? 0 : Q / A;
-				return [ (A + B) - b ];
+				roots[0] = (A + B) - b;
+				return 1;
 			}
-			return [];
+			return 0;
 		}
 	};
 };