diff --git a/components/script/script_runtime.rs b/components/script/script_runtime.rs
index fd3074d0b0c..649f39cac23 100644
--- a/components/script/script_runtime.rs
+++ b/components/script/script_runtime.rs
@@ -8,7 +8,8 @@
 #![allow(dead_code)]
 
 use core::ffi::c_char;
-use std::cell::Cell;
+use std::cell::{Cell, LazyCell, RefCell};
+use std::collections::HashSet;
 use std::ffi::CString;
 use std::io::{stdout, Write};
 use std::ops::Deref;
@@ -811,6 +812,10 @@ fn in_range<T: PartialOrd + Copy>(val: T, min: T, max: T) -> Option<T> {
     }
 }
 
+thread_local!(static SEEN_POINTERS: LazyCell<RefCell<HashSet<*const c_void>>> = const {
+    LazyCell::new(|| RefCell::new(HashSet::new()))
+});
+
 #[allow(unsafe_code)]
 unsafe extern "C" fn get_size(obj: *mut JSObject) -> usize {
     match get_dom_class(obj) {
@@ -820,7 +825,13 @@ unsafe extern "C" fn get_size(obj: *mut JSObject) -> usize {
             if dom_object.is_null() {
                 return 0;
             }
-            let mut ops = MallocSizeOfOps::new(servo_allocator::usable_size, None, None);
+            let seen_pointer =
+                move |ptr| SEEN_POINTERS.with(|pointers| !pointers.borrow_mut().insert(ptr));
+            let mut ops = MallocSizeOfOps::new(
+                servo_allocator::usable_size,
+                None,
+                Some(Box::new(seen_pointer)),
+            );
             (v.malloc_size_of)(&mut ops, dom_object)
         },
         Err(_e) => 0,
@@ -946,6 +957,7 @@ impl JSContext {
 
     #[allow(unsafe_code)]
     pub(crate) fn get_reports(&self, path_seg: String) -> Vec<Report> {
+        SEEN_POINTERS.with(|pointers| pointers.borrow_mut().clear());
         let stats = unsafe {
             let mut stats = ::std::mem::zeroed();
             if !CollectServoSizes(self.0, &mut stats, Some(get_size)) {
diff --git a/components/script/timers.rs b/components/script/timers.rs
index 60b079ebcf8..875b037533e 100644
--- a/components/script/timers.rs
+++ b/components/script/timers.rs
@@ -22,7 +22,7 @@ use crate::dom::bindings::codegen::Bindings::FunctionBinding::Function;
 use crate::dom::bindings::inheritance::Castable;
 use crate::dom::bindings::refcounted::Trusted;
 use crate::dom::bindings::reflector::DomObject;
-use crate::dom::bindings::root::DomRoot;
+use crate::dom::bindings::root::Dom;
 use crate::dom::bindings::str::DOMString;
 use crate::dom::document::FakeRequestAnimationFrameCallback;
 use crate::dom::eventsource::EventSourceTimeoutCallback;
@@ -40,8 +40,9 @@ use crate::task_source::SendableTaskSource;
 pub(crate) struct OneshotTimerHandle(i32);
 
 #[derive(DenyPublicFields, JSTraceable, MallocSizeOf)]
+#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
 pub(crate) struct OneshotTimers {
-    global_scope: DomRoot<GlobalScope>,
+    global_scope: Dom<GlobalScope>,
     js_timers: JsTimers,
     next_timer_handle: Cell<OneshotTimerHandle>,
     timers: DomRefCell<Vec<OneshotTimer>>,
@@ -121,7 +122,7 @@ impl PartialEq for OneshotTimer {
 impl OneshotTimers {
     pub(crate) fn new(global_scope: &GlobalScope) -> OneshotTimers {
         OneshotTimers {
-            global_scope: DomRoot::from_ref(global_scope),
+            global_scope: Dom::from_ref(global_scope),
             js_timers: JsTimers::default(),
             next_timer_handle: Cell::new(OneshotTimerHandle(1)),
             timers: DomRefCell::new(Vec::new()),