diff --git a/core/workspace_svg.js b/core/workspace_svg.js
index 84b9fa539..49475bf81 100644
--- a/core/workspace_svg.js
+++ b/core/workspace_svg.js
@@ -300,22 +300,37 @@ Blockly.WorkspaceSvg.prototype.targetWorkspace = null;
  */
 Blockly.WorkspaceSvg.prototype.inverseScreenCTM_ = null;
 
+/**
+ * Inverted screen CTM is dirty, recalculate it.
+ * @type {Boolean}
+ * @private
+ */
+Blockly.WorkspaceSvg.prototype.inverseScreenCTMDirty_ = true;
+
 /**
  * Getter for the inverted screen CTM.
  * @return {SVGMatrix} The matrix to use in mouseToSvg
  */
 Blockly.WorkspaceSvg.prototype.getInverseScreenCTM = function() {
+
+  // Defer getting the screen CTM until we actually need it, this should
+  // avoid forced reflows from any calls to updateInverseScreenCTM.
+  if (this.inverseScreenCTMDirty_) {
+    var ctm = this.getParentSvg().getScreenCTM();
+    if (ctm) {
+      this.inverseScreenCTM_ = ctm.inverse();
+      this.inverseScreenCTMDirty_ = false;
+    }
+  }
+
   return this.inverseScreenCTM_;
 };
 
 /**
- * Update the inverted screen CTM.
+ * Mark the inverse screen CTM as dirty.
  */
 Blockly.WorkspaceSvg.prototype.updateInverseScreenCTM = function() {
-  var ctm = this.getParentSvg().getScreenCTM();
-  if (ctm) {
-    this.inverseScreenCTM_ = ctm.inverse();
-  }
+  this.inverseScreenCTMDirty_ = true;
 };
 
 /**