--- a/browser/modules/AsyncTabSwitcher.jsm
+++ b/browser/modules/AsyncTabSwitcher.jsm
@@ -249,17 +249,19 @@ class AsyncTabSwitcher {
 
     this.setTabStateNoAction(tab, state);
 
     let browser = tab.linkedBrowser;
     let { tabParent } = browser.frameLoader;
     if (state == this.STATE_LOADING) {
       this.assert(!this.minimizedOrFullyOccluded);
 
-      if (!this.tabbrowser.tabWarmingEnabled) {
+      // If we're not in the process of warming this tab, we
+      // don't need to delay activating its DocShell.
+      if (!this.warmingTabs.has(tab)) {
         browser.docShellIsActive = true;
       }
 
       if (tabParent) {
         browser.renderLayers = true;
       } else {
         this.onLayersReady(browser);
       }