diff --git a/accessible/base/nsAccessibilityService.cpp b/accessible/base/nsAccessibilityService.cpp
index 483c0b7ef2f9..3b83b7c96383 100644
--- a/accessible/base/nsAccessibilityService.cpp
+++ b/accessible/base/nsAccessibilityService.cpp
@@ -48,6 +48,7 @@
 #ifdef XP_WIN
 #  include "mozilla/a11y/Compatibility.h"
 #  include "mozilla/dom/ContentChild.h"
+#  include "mozilla/StaticPrefs_accessibility.h"
 #  include "mozilla/StaticPtr.h"
 #endif
 
@@ -1222,7 +1223,8 @@ bool nsAccessibilityService::Init() {
     MOZ_ASSERT(contentChild);
     // If we were instantiated by the chrome process, GetMsaaID() will return
     // a non-zero value and we may safely continue with initialization.
-    if (!contentChild->GetMsaaID()) {
+    if (!StaticPrefs::accessibility_cache_enabled_AtStartup() &&
+        !contentChild->GetMsaaID()) {
       // Since we were not instantiated by chrome, we need to synchronously
       // obtain a MSAA content process id.
       contentChild->SendGetA11yContentId();
diff --git a/accessible/windows/msaa/MsaaAccessible.cpp b/accessible/windows/msaa/MsaaAccessible.cpp
index 02c6c45890d7..90658439909c 100644
--- a/accessible/windows/msaa/MsaaAccessible.cpp
+++ b/accessible/windows/msaa/MsaaAccessible.cpp
@@ -169,6 +169,9 @@ int32_t MsaaAccessible::GetChildIDFor(Accessible* aAccessible) {
 /* static */
 uint32_t MsaaAccessible::GetContentProcessIdFor(
     dom::ContentParentId aIPCContentId) {
+  if (StaticPrefs::accessibility_cache_enabled_AtStartup()) {
+    return 0;
+  }
   return sIDGen.GetContentProcessIDFor(aIPCContentId);
 }
 
diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp
index eabf2a664023..56fb912cb1a5 100644
--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -43,6 +43,7 @@
 #include "mozilla/SharedStyleSheetCache.h"
 #include "mozilla/SimpleEnumerator.h"
 #include "mozilla/SpinEventLoopUntil.h"
+#include "mozilla/StaticPrefs_accessibility.h"
 #include "mozilla/StaticPrefs_dom.h"
 #include "mozilla/StaticPrefs_fission.h"
 #include "mozilla/StaticPrefs_media.h"
@@ -2469,7 +2470,8 @@ mozilla::ipc::IPCResult ContentChild::RecvActivateA11y(
   MOZ_ASSERT(aMainChromeTid != 0);
   mMainChromeTid = aMainChromeTid;
 
-  MOZ_ASSERT(aMsaaID != 0);
+  MOZ_ASSERT(StaticPrefs::accessibility_cache_enabled_AtStartup() ? !aMsaaID
+                                                                  : aMsaaID);
   mMsaaID = aMsaaID;
 #  endif  // XP_WIN