diff --git a/inventory/static/js/components/draw.js b/inventory/static/js/components/draw.js
index 8b8969f..a2a9a57 100644
--- a/inventory/static/js/components/draw.js
+++ b/inventory/static/js/components/draw.js
@@ -574,10 +574,59 @@ function initGridWidget(root, opts = {}) {
         });
     }
 
+    function totalTurning(points) {
+        let sum = 0;
+
+        for (let i = 1; i < points.length - 1; i++) {
+            const p0 = points[i - 1];
+            const p1 = points[i];
+            const p2 = points[i + 1];
+
+            const v1x = p1.x - p0.x;
+            const v1y = p1.y - p0.y;
+            const v2x = p2.x - p1.x;
+            const v2y = p2.y - p1.y;
+
+            const len1 = Math.hypot(v1x, v1y);
+            const len2 = Math.hypot(v2x, v2y);
+
+            if (len1 === 0 || len2 === 0) continue;
+
+            const cross = Math.abs(v1x * v2y - v1y * v2x);
+
+            sum += cross / (len1 * len2);
+        }
+
+        return sum;
+    }
+
+    function pathLength(pts) {
+        let L = 0;
+        for (let i = 1; i < pts.length; i++) {
+            const dx = pts[i].x - pts[i-1].x;
+            const dy = pts[i].y - pts[i-1].y;
+            L += Math.hypot(dx, dy);
+        }
+        return L;
+    }
+
     function rebuildPathCaches(list) {
+        const MIN_PTS_FOR_SMOOTH = 4;
+        const MIN_LEN = 2;
+        const MIN_TURN = 0.15;
+
         return list.map(s => {
             if (s.type !== 'path') return s;
-            if (!Array.isArray(s.points) || s.points.length < 2) return s;
+
+            const pts = s.points;
+            if (!Array.isArray(s.points) || pts.length < 2) return s;
+            if (!pts.every(p => p && Number.isFinite(p.x) && Number.isFinite(p.y))) return s;
+
+            if (pathLength(pts) < MIN_LEN) return s;
+
+            if (pts.length < MIN_PTS_FOR_SMOOTH) return s;
+
+            if (MIN_TURN != null && totalTurning(pts) < MIN_TURN) return s;
 
             const renderPoints = catmullRomResample(s.points, {
                 alpha: 0.5,
@@ -1076,11 +1125,32 @@ function initGridWidget(root, opts = {}) {
         ctx.restore();
     }
 
-    function penAddPoint(shape, clientX, clientY, minStep = 0.02) {
+    function penAddPoint(shape, clientX, clientY, minStep = 0.02, maxDtMs = 16) {
         const p = pxToDocPoint(clientX, clientY);
+
+        if (!Array.isArray(shape.points)) shape.points = [];
+        if (shape._lastAddTime == null) shape._lastAddTime = performance.now();
+
         const pts = shape.points;
         const last = pts[pts.length - 1];
-        if (!last || dist2(p, last) >= minStep * minStep) pts.push(p);
+
+        const now = performance.now();
+        const dt = now - shape._lastAddTime;
+
+        if (!last) {
+            pts.push(p);
+            shape._lastAddTime = now;
+            return;
+        }
+
+        const dx = p.x - last.x;
+        const dy = p.y - last.y;
+        const d2 = dx * dx + dy * dy;
+
+        if (d2 >= minStep * minStep || dt >= maxDtMs) {
+            pts.push(p);
+            shape._lastAddTime = now;
+        }
     }
 
     function pxToDocPoint(clientX, clientY) {
@@ -1600,6 +1670,7 @@ function initGridWidget(root, opts = {}) {
         }
 
         if (finalShape) {
+            if (finalShape && ('_lastAddTime' in finalShape)) delete finalShape._lastAddTime;
             commit([...shapes, finalShape]);
 
 
@@ -1827,7 +1898,14 @@ function initGridWidget(root, opts = {}) {
 
         // PEN: mutate points and preview the same shape object
         if (currentShape.tool === 'pen') {
-            penAddPoint(currentShape, e.clientX, e.clientY, 0.02);
+            const minStepPx = 0.75;
+            const minStep = minStepPx / cellSize;
+            penAddPoint(currentShape, e.clientX, e.clientY, minStep, 16);
+
+            // realtime instrumentation
+            coordsEl.innerText += ` | pts=${currentShape.points?.length ?? 0}`;
+            console.log("move", e.pointerId, performance.now());
+
             renderAllWithPreview(currentShape, false);
             return;
         }
@@ -1925,7 +2003,8 @@ function initGridWidget(root, opts = {}) {
                 points: [p],
                 color: selectedColor,
                 strokeWidth: currentStrokeWidth,
-                strokeOpacity: currentStrokeOpacity
+                strokeOpacity: currentStrokeOpacity,
+                _lastAddTime: performance.now()
             };
         }
     });