diff --git a/src/syncback/mod.rs b/src/syncback/mod.rs
index 7e305fa2..c76ba5a1 100644
--- a/src/syncback/mod.rs
+++ b/src/syncback/mod.rs
@@ -44,6 +44,26 @@ pub use snapshot::{inst_path, SyncbackData, SyncbackSnapshot};
 /// new files.
 const DEBUG_MODEL_FORMAT_VAR: &str = "ROJO_SYNCBACK_DEBUG";
 
+/// Services that are considered "visible" and will be included when
+/// `ignoreHiddenServices` is enabled. All other services will be ignored.
+const VISIBLE_SERVICES: &[&str] = &[
+    "Lighting",
+    "MaterialService",
+    "NetworkClient",
+    "ReplicatedFirst",
+    "ReplicatedStorage",
+    "ServerScriptService",
+    "ServerStorage",
+    "SoundService",
+    "StarterGui",
+    "StarterPack",
+    "StarterPlayer",
+    "Teams",
+    "TextChatService",
+    "VoiceChatService",
+    "Workspace",
+];
+
 /// A glob that can be used to tell if a path contains a `.git` folder.
 static GIT_IGNORE_GLOB: OnceLock<Glob> = OnceLock::new();
 
@@ -91,6 +111,17 @@ pub fn syncback_loop(
         strip_unknown_root_children(&mut new_tree, old_tree);
     }
 
+    // If ignoreHiddenServices is enabled, filter to only visible services
+    if project
+        .syncback_rules
+        .as_ref()
+        .map(|rules| rules.ignore_hidden_services())
+        .unwrap_or(false)
+    {
+        log::debug!("Filtering hidden services");
+        strip_hidden_services(&mut new_tree);
+    }
+
     log::debug!("Collecting referents for new DOM...");
     let deferred_referents = collect_referents(&new_tree, &pre_prune_paths);
 
@@ -408,6 +439,12 @@ pub struct SyncbackRules {
     /// Defaults to `false`.
     #[serde(skip_serializing_if = "Option::is_none")]
     encode_windows_invalid_chars: Option<bool>,
+    /// When enabled, only "visible" services will be synced back. This includes
+    /// commonly used services like Workspace, ReplicatedStorage, ServerScriptService,
+    /// etc., while ignoring internal/hidden services like Chat, HttpService, etc.
+    /// Defaults to `false`.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    ignore_hidden_services: Option<bool>,
 }
 
 impl SyncbackRules {
@@ -453,6 +490,14 @@ impl SyncbackRules {
     pub fn encode_windows_invalid_chars(&self) -> bool {
         self.encode_windows_invalid_chars.unwrap_or(true)
     }
+
+    /// Returns whether hidden/internal services should be ignored during
+    /// syncback. When `true`, only visible services like Workspace,
+    /// ReplicatedStorage, etc. will be synced. Defaults to `false`.
+    #[inline]
+    pub fn ignore_hidden_services(&self) -> bool {
+        self.ignore_hidden_services.unwrap_or(false)
+    }
 }
 
 fn is_valid_path(globs: &Option<Vec<Glob>>, base_path: &Path, path: &Path) -> bool {
@@ -524,6 +569,29 @@ fn descendants(dom: &WeakDom, root_ref: Ref) -> Vec<Ref> {
     ordered
 }
 
+/// Removes root children (services) that are not in the `VISIBLE_SERVICES` list.
+/// This is used when `ignoreHiddenServices` is enabled to filter out internal
+/// services like Chat, HttpService, etc.
+fn strip_hidden_services(dom: &mut WeakDom) {
+    let root_children = dom.root().children().to_vec();
+
+    for child_ref in root_children {
+        let child = dom
+            .get_by_ref(child_ref)
+            .expect("all children of the root should exist in the DOM");
+
+        // Check if this service is in the visible services list
+        if !VISIBLE_SERVICES.contains(&child.name.as_str()) {
+            log::trace!(
+                "Pruning hidden service {} of class {}",
+                child.name,
+                child.class
+            );
+            dom.destroy(child_ref);
+        }
+    }
+}
+
 /// Removes the children of `new`'s root that are not also children of `old`'s
 /// root.
 ///
diff --git a/src/syncback/ref_properties.rs b/src/syncback/ref_properties.rs
index 9d251585..871e19d8 100644
--- a/src/syncback/ref_properties.rs
+++ b/src/syncback/ref_properties.rs
@@ -51,13 +51,60 @@ pub fn collect_all_paths(dom: &WeakDom) -> HashMap<Ref, String> {
     paths
 }
 
-/// Checks if a path is unique in the DOM by verifying no duplicates exist
-/// at ANY level of the path (target, parent, grandparent, etc.).
-fn is_path_unique(dom: &WeakDom, target_ref: Ref) -> bool {
+/// Pre-computes which instances have duplicate-named siblings.
+/// Returns a HashSet of Refs that have at least one sibling with the same name.
+///
+/// This is O(N) where N is the number of instances, and allows subsequent
+/// path uniqueness checks to be O(d) instead of O(d × s) where d=depth, s=siblings.
+fn compute_refs_with_duplicate_siblings(dom: &WeakDom) -> HashSet<Ref> {
+    let mut has_duplicate_siblings = HashSet::new();
+    let mut queue = VecDeque::new();
+    queue.push_back(dom.root_ref());
+
+    while let Some(inst_ref) = queue.pop_front() {
+        let inst = match dom.get_by_ref(inst_ref) {
+            Some(i) => i,
+            None => continue,
+        };
+
+        // Count children by name and collect their refs
+        let mut name_to_refs: HashMap<&str, Vec<Ref>> = HashMap::new();
+        for child_ref in inst.children() {
+            if let Some(child) = dom.get_by_ref(*child_ref) {
+                name_to_refs.entry(&child.name).or_default().push(*child_ref);
+            }
+            queue.push_back(*child_ref);
+        }
+
+        // Mark refs that share a name with siblings
+        for (_name, refs) in name_to_refs {
+            if refs.len() > 1 {
+                for r in refs {
+                    has_duplicate_siblings.insert(r);
+                }
+            }
+        }
+    }
+
+    has_duplicate_siblings
+}
+
+/// Checks if a path is unique using pre-computed duplicate sibling info.
+/// This is O(d) where d is the depth of the instance.
+fn is_path_unique_with_cache(
+    dom: &WeakDom,
+    target_ref: Ref,
+    has_duplicate_siblings: &HashSet<Ref>,
+) -> bool {
     let mut current_ref = target_ref;
 
-    // Walk up the tree checking each level for duplicate names among siblings
+    // Walk up the tree checking each level using the pre-computed cache
     loop {
+        // O(1) lookup instead of O(siblings) counting
+        if has_duplicate_siblings.contains(&current_ref) {
+            return false;
+        }
+
         let current = match dom.get_by_ref(current_ref) {
             Some(inst) => inst,
             None => return false,
@@ -69,26 +116,6 @@ fn is_path_unique(dom: &WeakDom, target_ref: Ref) -> bool {
             return true;
         }
 
-        let parent = match dom.get_by_ref(parent_ref) {
-            Some(inst) => inst,
-            None => return true,
-        };
-
-        // Check if any sibling has the same name as current
-        let current_name = &current.name;
-        let mut count = 0;
-        for child_ref in parent.children() {
-            if let Some(child) = dom.get_by_ref(*child_ref) {
-                if &child.name == current_name {
-                    count += 1;
-                    if count > 1 {
-                        // Duplicate found at this level - path is not unique
-                        return false;
-                    }
-                }
-            }
-        }
-
         // Move up to parent and check the next level
         current_ref = parent_ref;
     }
@@ -105,6 +132,13 @@ pub fn collect_referents(dom: &WeakDom, pre_prune_paths: &HashMap<Ref, String>)
     let mut id_links: HashMap<Ref, Vec<IdRefLink>> = HashMap::new();
     let mut targets_needing_id: HashSet<Ref> = HashSet::new();
 
+    // Pre-compute duplicate sibling info in O(N) - this makes all subsequent
+    // path uniqueness checks O(d) instead of O(d × s) where d=depth, s=siblings
+    let has_duplicate_siblings = compute_refs_with_duplicate_siblings(dom);
+
+    // Cache path uniqueness results to avoid re-checking the same target
+    let mut path_unique_cache: HashMap<Ref, bool> = HashMap::new();
+
     let mut queue = VecDeque::new();
     queue.push_back(dom.root_ref());
 
@@ -122,8 +156,12 @@ pub fn collect_referents(dom: &WeakDom, pre_prune_paths: &HashMap<Ref, String>)
 
             // Check if target exists in current DOM
             if let Some(_target) = dom.get_by_ref(*target_ref) {
-                // Target exists - check if path is unique
-                if is_path_unique(dom, *target_ref) {
+                // Target exists - check if path is unique (with caching)
+                let is_unique = *path_unique_cache
+                    .entry(*target_ref)
+                    .or_insert_with(|| is_path_unique_with_cache(dom, *target_ref, &has_duplicate_siblings));
+
+                if is_unique {
                     // Path is unique - use path-based system
                     let target_path = inst_path(dom, *target_ref);
                     path_links.entry(inst_ref).or_default().push(PathRefLink {
diff --git a/src/web/api.rs b/src/web/api.rs
index 2b32fac0..353438ab 100644
--- a/src/web/api.rs
+++ b/src/web/api.rs
@@ -221,13 +221,24 @@ impl ApiService {
         }
 
         // Process added instances (syncback: create files from Studio instances)
-        for added in request.added.values() {
-            if let Err(err) = self.syncback_added_instance(added) {
-                log::warn!(
-                    "Failed to syncback added instance '{}': {}",
-                    added.name,
-                    err
-                );
+        // We hold the tree lock during the entire processing to ensure the cache
+        // remains consistent with the tree state being checked.
+        if !request.added.is_empty() {
+            let tree = self.serve_session.tree();
+            // Pre-compute duplicate sibling info in O(N) for efficient path uniqueness checks
+            // This makes all subsequent path checks O(d) instead of O(d × s)
+            let duplicate_siblings_cache = Self::compute_tree_refs_with_duplicate_siblings(&tree);
+
+            for added in request.added.values() {
+                if let Err(err) =
+                    self.syncback_added_instance(added, &tree, &duplicate_siblings_cache)
+                {
+                    log::warn!(
+                        "Failed to syncback added instance '{}': {}",
+                        added.name,
+                        err
+                    );
+                }
             }
         }
 
@@ -257,13 +268,73 @@ impl ApiService {
     /// Syncback an added instance by creating a file in the filesystem.
     /// The file watcher will pick up the change and update Rojo's tree.
     ///
-    /// Checks if a path in the Rojo tree is unique by verifying no duplicates exist
-    /// at ANY level of the path (similar to ref_properties::is_path_unique).
+    /// Pre-computes which instances have duplicate-named siblings in a RojoTree.
+    /// Returns a HashSet of Refs that have at least one sibling with the same name.
+    ///
+    /// This is O(N) where N is the number of instances, and allows subsequent
+    /// path uniqueness checks to be O(d) instead of O(d × s) where d=depth, s=siblings.
+    fn compute_tree_refs_with_duplicate_siblings(
+        tree: &crate::snapshot::RojoTree,
+    ) -> HashSet<Ref> {
+        use std::collections::VecDeque;
+
+        let mut has_duplicate_siblings = HashSet::new();
+        let mut queue = VecDeque::new();
+        queue.push_back(tree.root().id());
+
+        while let Some(inst_ref) = queue.pop_front() {
+            let inst = match tree.get_instance(inst_ref) {
+                Some(i) => i,
+                None => continue,
+            };
+
+            // Count children by name and collect their refs
+            let mut name_to_refs: HashMap<&str, Vec<Ref>> = HashMap::new();
+            for child_ref in inst.children() {
+                if let Some(child) = tree.get_instance(*child_ref) {
+                    name_to_refs.entry(child.name()).or_default().push(*child_ref);
+                }
+                queue.push_back(*child_ref);
+            }
+
+            // Mark refs that share a name with siblings
+            for (_name, refs) in name_to_refs {
+                if refs.len() > 1 {
+                    for r in refs {
+                        has_duplicate_siblings.insert(r);
+                    }
+                }
+            }
+        }
+
+        has_duplicate_siblings
+    }
+
+    /// Checks if a path in the Rojo tree is unique using pre-computed duplicate sibling info.
     /// Returns true if the path is unique, false if duplicates exist at any level.
-    fn is_tree_path_unique(&self, tree: &crate::snapshot::RojoTree, target_ref: Ref) -> bool {
+    /// This is O(d) where d is the depth of the instance.
+    fn is_tree_path_unique_with_cache(
+        tree: &crate::snapshot::RojoTree,
+        target_ref: Ref,
+        has_duplicate_siblings: &HashSet<Ref>,
+    ) -> bool {
         let mut current_ref = target_ref;
 
         loop {
+            // O(1) lookup instead of O(siblings) counting
+            if has_duplicate_siblings.contains(&current_ref) {
+                if let Some(current) = tree.get_instance(current_ref) {
+                    if let Some(parent) = tree.get_instance(current.parent()) {
+                        log::warn!(
+                            "Syncback: Path to '{}' is not unique - duplicate-named siblings at '{}'",
+                            current.name(),
+                            parent.name()
+                        );
+                    }
+                }
+                return false;
+            }
+
             let current = match tree.get_instance(current_ref) {
                 Some(inst) => inst,
                 None => return false,
@@ -275,31 +346,6 @@ impl ApiService {
                 return true;
             }
 
-            let parent = match tree.get_instance(parent_ref) {
-                Some(inst) => inst,
-                None => return true,
-            };
-
-            // Check if any sibling has the same name as current
-            let current_name = current.name();
-            let mut count = 0;
-            for child_ref in parent.children() {
-                if let Some(child) = tree.get_instance(*child_ref) {
-                    if child.name() == current_name {
-                        count += 1;
-                        if count > 1 {
-                            // Duplicate found at this level - path is not unique
-                            log::warn!(
-                                "Syncback: Path to '{}' is not unique - duplicate-named siblings at '{}'",
-                                current_name,
-                                parent.name()
-                            );
-                            return false;
-                        }
-                    }
-                }
-            }
-
             // Move up to parent and check the next level
             current_ref = parent_ref;
         }
@@ -307,9 +353,14 @@ impl ApiService {
 
     /// This follows the same middleware selection logic as the dedicated syncback
     /// system in `src/syncback/mod.rs` to ensure consistent behavior.
+    ///
+    /// Takes the tree reference and duplicate siblings cache as parameters to ensure
+    /// consistency - the cache was computed from this exact tree state.
     fn syncback_added_instance(
         &self,
         added: &crate::web::interface::AddedInstance,
+        tree: &crate::snapshot::RojoTree,
+        duplicate_siblings_cache: &HashSet<Ref>,
     ) -> anyhow::Result<()> {
         use crate::syncback::validate_file_name;
         use anyhow::Context;
@@ -323,13 +374,13 @@ impl ApiService {
         })?;
 
         // Find the parent instance to get its filesystem path
-        let tree = self.serve_session.tree();
         let parent_instance = tree
             .get_instance(added.parent)
             .context("Parent instance not found in Rojo tree")?;
 
         // Check if the parent path is unique (no duplicate-named siblings at any level)
-        if !self.is_tree_path_unique(&tree, added.parent) {
+        // Uses pre-computed cache for O(d) instead of O(d × s) complexity
+        if !Self::is_tree_path_unique_with_cache(tree, added.parent, duplicate_siblings_cache) {
             anyhow::bail!(
                 "Cannot sync instance '{}' - parent path contains duplicate-named siblings",
                 added.name