diff --git a/notes.md b/notes.md
index 6febadc0..d18a1ba0 100644
--- a/notes.md
+++ b/notes.md
@@ -10,7 +10,6 @@
 *   drag knife support
 * all
 *   2d image to 3d part
-*   memory optimization (worker and client proactive cleanup)
 *   circular fit/layout when no-layout to prevent collisions
 
 ## 2.5 roadmap
diff --git a/package.json b/package.json
index 43574725..c3c662b1 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "grid-apps",
-    "version": "2.4.4D",
+    "version": "2.4.5D",
     "description": "grid.space 3d slice & modeling tools",
     "author": "Stewart Allen <sa@grid.space>",
     "license": "MIT",
diff --git a/src/kiri/main.js b/src/kiri/main.js
index 638ce614..9720450c 100644
--- a/src/kiri/main.js
+++ b/src/kiri/main.js
@@ -754,7 +754,7 @@
             let segtimes = {},
                 segNumber = 0,
                 errored = false,
-                startTime,
+                startTime = Date.now(),
                 lastMsg,
                 camOrLaser = mode === 'CAM' || mode === 'LASER',
                 stack = STACKS.create(widget.id, widget.mesh);
@@ -802,7 +802,7 @@
                     alert2(error);
                 }
             }, function(update, msg) {
-                if (msg !== lastMsg) {
+                if (msg && msg !== lastMsg) {
                     let mark = Date.now();
                     if (lastMsg) {
                         segtimes[`${segNumber++}_${lastMsg}`] = mark - startTime;
@@ -862,7 +862,7 @@
             if (layer) {
                 output.push(KIRI.codec.decode(layer));
             }
-            if (message !== lastMsg) {
+            if (message && message !== lastMsg) {
                 let mark = Date.now();
                 if (lastMsg) {
                     segtimes[`${segNumber++}_${lastMsg}`] = mark - startTime;
diff --git a/src/kiri/slicer.js b/src/kiri/slicer.js
index 6164b5bf..b71f1ea3 100644
--- a/src/kiri/slicer.js
+++ b/src/kiri/slicer.js
@@ -488,8 +488,12 @@
                 if (where.under.length === 3 || where.over.length === 3) {
                     // does not intersect (all 3 above or below)
                 } else if (where.on.length === 2) {
-                    // one side of triangle is on the Z plane
-                    lines.push(makeZLine(phash, where.on[0], where.on[1], false, true));
+                    // one side of triangle is on the Z plane and 3rd is below
+                    // drop lines with 3rd above because that leads to ambiguities
+                    // with complex nested polygons on flat surface
+                    if (where.under.length === 1) {
+                        lines.push(makeZLine(phash, where.on[0], where.on[1], false, true));
+                    }
                 } else if (where.on.length === 3) {
                     // triangle is coplanar with Z
                     // we drop these because this face is attached to 3 others
diff --git a/src/kiri/slicer2.js b/src/kiri/slicer2.js
index 0d094cfc..12f19a32 100644
--- a/src/kiri/slicer2.js
+++ b/src/kiri/slicer2.js
@@ -233,8 +233,12 @@
                 if (where.under.length === 3 || where.over.length === 3) {
                     // does not intersect (all 3 above or below)
                 } else if (where.on.length === 2) {
-                    // one side of triangle is on the Z plane
-                    lines.push(makeZLine(phash, where.on[0], where.on[1], false, true));
+                    // one side of triangle is on the Z plane and 3rd is below
+                    // drop lines with 3rd above because that leads to ambiguities
+                    // with complex nested polygons on flat surface
+                    if (where.under.length === 1) {
+                        lines.push(makeZLine(phash, where.on[0], where.on[1], false, true));
+                    }
                 } else if (where.on.length === 3) {
                     // triangle is coplanar with Z
                     // we drop these because this face is attached to 3 others
diff --git a/src/license.js b/src/license.js
index 3ed8b333..afb368bd 100644
--- a/src/license.js
+++ b/src/license.js
@@ -3,7 +3,7 @@
     let terms = {
         COPYRIGHT: "Copyright (C) Stewart Allen <sa@grid.space> - All Rights Reserved",
         LICENSE: "See the license.md file included with the source distribution",
-        VERSION: "2.4.D4"
+        VERSION: "2.4.D5"
     };
 
     if (typeof(module) === 'object') {