diff --git a/devtools/client/inspector/components/InspectorTabPanel.js b/devtools/client/inspector/components/InspectorTabPanel.js
index 677ddf96a74a..020e8d405bc5 100644
--- a/devtools/client/inspector/components/InspectorTabPanel.js
+++ b/devtools/client/inspector/components/InspectorTabPanel.js
@@ -25,8 +25,10 @@ class InspectorTabPanel extends Component {
       id: PropTypes.string.isRequired,
       // Optional prefix for panel IDs.
       idPrefix: PropTypes.string,
-      // Optional mount callback
+      // Optional mount callback.
       onMount: PropTypes.func,
+      // Optional unmount callback.
+      onUnmount: PropTypes.func,
     };
   }
 
@@ -52,6 +54,10 @@ class InspectorTabPanel extends Component {
     let doc = this.refs.content.ownerDocument;
     let panels = doc.getElementById("tabpanels");
 
+    if (this.props.onUnmount) {
+      this.props.onUnmount(this.refs.content, this.props);
+    }
+
     // Move panel's content node back into list of tab panels.
     panels.appendChild(this.refs.content.firstChild);
   }
diff --git a/devtools/client/inspector/toolsidebar.js b/devtools/client/inspector/toolsidebar.js
index 5afeaf2bad75..056af4a4fa87 100644
--- a/devtools/client/inspector/toolsidebar.js
+++ b/devtools/client/inspector/toolsidebar.js
@@ -137,6 +137,7 @@ ToolSidebar.prototype = {
       title: title,
       url: url,
       onMount: this.onSidePanelMounted.bind(this),
+      onUnmount: this.onSidePanelUnmounted.bind(this),
     });
 
     this.addTab(id, title, panel, selected, index);
@@ -163,6 +164,20 @@ ToolSidebar.prototype = {
     iframe.setAttribute("src", props.url);
   },
 
+  onSidePanelUnmounted: function (content, props) {
+    let iframe = content.querySelector("iframe");
+    if (!iframe || !iframe.hasAttribute("src")) {
+      return;
+    }
+
+    let win = iframe.contentWindow;
+    if ("destroy" in win) {
+      win.destroy(this._toolPanel, iframe);
+    }
+
+    iframe.removeAttribute("src");
+  },
+
   /**
    * Remove an existing tab.
    * @param {String} tabId The ID of the tab that was used to register it, or
diff --git a/devtools/client/jsonview/components/MainTabbedArea.js b/devtools/client/jsonview/components/MainTabbedArea.js
index 431ed4ad80fd..888f2a093c32 100644
--- a/devtools/client/jsonview/components/MainTabbedArea.js
+++ b/devtools/client/jsonview/components/MainTabbedArea.js
@@ -61,6 +61,7 @@ define(function (require, exports, module) {
           tabActive: this.state.tabActive,
           onAfterChange: this.onTabChanged},
           TabPanel({
+            id: "json",
             className: "json",
             title: JSONView.Locale.$STR("jsonViewer.tab.JSON")},
             JsonPanel({
@@ -71,6 +72,7 @@ define(function (require, exports, module) {
             })
           ),
           TabPanel({
+            id: "rawdata",
             className: "rawdata",
             title: JSONView.Locale.$STR("jsonViewer.tab.RawData")},
             TextPanel({
@@ -81,6 +83,7 @@ define(function (require, exports, module) {
             })
           ),
           TabPanel({
+            id: "headers",
             className: "headers",
             title: JSONView.Locale.$STR("jsonViewer.tab.Headers")},
             HeadersPanel({
diff --git a/devtools/client/shared/components/tabs/Tabs.js b/devtools/client/shared/components/tabs/Tabs.js
index 164bfab77da4..03cef3fec673 100644
--- a/devtools/client/shared/components/tabs/Tabs.js
+++ b/devtools/client/shared/components/tabs/Tabs.js
@@ -72,14 +72,15 @@ define(function (require, exports, module) {
       this.state = {
         tabActive: props.tabActive,
 
-        // This array is used to store an information whether a tab
-        // at specific index has already been created (e.g. selected
-        // at least once).
-        // If yes, it's rendered even if not currently selected.
-        // This is because in some cases we don't want to re-create
-        // tab content when it's being unselected/selected.
-        // E.g. in case of an iframe being used as a tab-content
-        // we want the iframe to stay in the DOM.
+        // This array is used to store an object containing information on whether a tab
+        // at a specified index has already been created (e.g. selected at least once) and
+        // the tab id. An example of the object structure is the following:
+        // [{ isCreated: true, tabId: "ruleview" }, { isCreated: false, tabId: "foo" }].
+        // If the tab at the specified index has already been created, it's rendered even
+        // if not currently selected. This is because in some cases we don't want
+        // to re-create tab content when it's being unselected/selected.
+        // E.g. in case of an iframe being used as a tab-content we want the iframe to
+        // stay in the DOM.
         created: [],
 
         // True if tabs can't fit into available horizontal space.
@@ -116,24 +117,46 @@ define(function (require, exports, module) {
 
     componentWillReceiveProps(nextProps) {
       let { children, tabActive } = nextProps;
+      let panels = children.filter(panel => panel);
+      let created = [...this.state.created];
 
-      // Check type of 'tabActive' props to see if it's valid
-      // (it's 0-based index).
+      // If the children props has changed due to an addition or removal of a tab,
+      // update the state's created array with the latest tab ids and whether or not
+      // the tab is already created.
+      if (this.state.created.length != panels.length) {
+        created = panels.map(panel => {
+          // Get whether or not the tab has already been created from the previous state.
+          let createdEntry = this.state.created.find(entry => {
+            return entry && entry.tabId === panel.props.id;
+          });
+          let isCreated = !!createdEntry && createdEntry.isCreated;
+          let tabId = panel.props.id;
+
+          return {
+            isCreated,
+            tabId,
+          };
+        });
+      }
+
+      // Check type of 'tabActive' props to see if it's valid (it's 0-based index).
       if (typeof tabActive === "number") {
-        let panels = children.filter((panel) => panel);
-
         // Reset to index 0 if index overflows the range of panel array
         tabActive = (tabActive < panels.length && tabActive >= 0) ?
           tabActive : 0;
 
-        let created = [...this.state.created];
-        created[tabActive] = true;
+        created[tabActive] = Object.assign({}, created[tabActive], {
+          isCreated: true,
+        });
 
         this.setState({
-          created,
           tabActive,
         });
       }
+
+      this.setState({
+        created,
+      });
     }
 
     componentWillUnmount() {
@@ -209,11 +232,13 @@ define(function (require, exports, module) {
       }
 
       let created = [...this.state.created];
-      created[index] = true;
+      created[index] = Object.assign({}, created[index], {
+        isCreated: true,
+      });
 
       let newState = Object.assign({}, this.state, {
+        created,
         tabActive: index,
-        created: created
       });
 
       this.setState(newState, () => {
@@ -335,6 +360,8 @@ define(function (require, exports, module) {
           }
 
           let id = tab.props.id;
+          let isCreated = this.state.created[index] &&
+            this.state.created[index].isCreated;
 
           // Use 'visibility:hidden' + 'height:0' for hiding content of non-selected
           // tab. It's faster than 'display:none' because it avoids triggering frame
@@ -354,13 +381,13 @@ define(function (require, exports, module) {
           return (
             dom.div({
               id: id ? id + "-panel" : "panel-" + index,
-              key: index,
+              key: id,
               style: style,
               className: selected ? "tab-panel-box" : "tab-panel-box hidden",
               role: "tabpanel",
               "aria-labelledby": id ? id + "-tab" : "tab-" + index,
             },
-              (selected || this.state.created[index]) ? panel : null
+              (selected || isCreated) ? panel : null
             )
           );
         });
@@ -388,6 +415,8 @@ define(function (require, exports, module) {
   class Panel extends Component {
     static get propTypes() {
       return {
+        id: PropTypes.string.isRequired,
+        className: PropTypes.string,
         title: PropTypes.string.isRequired,
         children: PropTypes.oneOfType([
           PropTypes.array,
diff --git a/devtools/client/webconsole/net/components/net-info-body.js b/devtools/client/webconsole/net/components/net-info-body.js
index a335b340abf7..d6137d4edfc1 100644
--- a/devtools/client/webconsole/net/components/net-info-body.js
+++ b/devtools/client/webconsole/net/components/net-info-body.js
@@ -98,6 +98,7 @@ class NetInfoBody extends Component {
     // Headers tab
     panels.push(
       TabPanel({
+        id: "headers",
         className: "headers",
         key: "headers",
         title: Locale.$STR("netRequest.headers")},
@@ -109,6 +110,7 @@ class NetInfoBody extends Component {
     if (hasParams) {
       panels.push(
         TabPanel({
+          id: "params",
           className: "params",
           key: "params",
           title: Locale.$STR("netRequest.params")},
@@ -121,6 +123,7 @@ class NetInfoBody extends Component {
     if (hasPostData) {
       panels.push(
         TabPanel({
+          id: "post",
           className: "post",
           key: "post",
           title: Locale.$STR("netRequest.post")},
@@ -131,7 +134,10 @@ class NetInfoBody extends Component {
 
     // Response tab
     panels.push(
-      TabPanel({className: "response", key: "response",
+      TabPanel({
+        id: "response",
+        className: "response",
+        key: "response",
         title: Locale.$STR("netRequest.response")},
         ResponseTab({data: data, actions: actions})
       )
@@ -141,6 +147,7 @@ class NetInfoBody extends Component {
     if (this.hasCookies()) {
       panels.push(
         TabPanel({
+          id: "cookies",
           className: "cookies",
           key: "cookies",
           title: Locale.$STR("netRequest.cookies")},
@@ -156,6 +163,7 @@ class NetInfoBody extends Component {
     if (this.hasStackTrace()) {
       panels.push(
         TabPanel({
+          id: "stacktrace-tab",
           className: "stacktrace-tab",
           key: "stacktrace",
           title: Locale.$STR("netRequest.callstack")},