diff --git a/Realm/RLMCollection.mm b/Realm/RLMCollection.mm
index 416a82f808..380a9d1484 100644
--- a/Realm/RLMCollection.mm
+++ b/Realm/RLMCollection.mm
@@ -527,7 +527,7 @@ - (bool)invalidate {
     }
 
     RLMThreadSafeReference *tsr = [RLMThreadSafeReference referenceWithThreadConfined:collection];
-    RLMRealmConfiguration *config = realm.configuration;
+    RLMRealmConfiguration *config = realm.configurationSharingSchema;
     dispatch_async(queue, ^{
         std::lock_guard lock(token->_mutex);
         if (!token->_realm) {
diff --git a/Realm/RLMObjectBase.mm b/Realm/RLMObjectBase.mm
index a31310fe43..0cc1b5a114 100644
--- a/Realm/RLMObjectBase.mm
+++ b/Realm/RLMObjectBase.mm
@@ -790,7 +790,7 @@ - (void)registrationComplete:(void (^)())completion {
     RLMThreadSafeReference *tsr = [RLMThreadSafeReference referenceWithThreadConfined:(id)obj];
     auto token = [[RLMObjectNotificationToken alloc] init];
     token->_realm = obj->_realm;
-    RLMRealmConfiguration *config = obj->_realm.configuration;
+    RLMRealmConfiguration *config = obj->_realm.configurationSharingSchema;
     dispatch_async(queue, ^{
         @autoreleasepool {
             [token addNotificationBlock:block threadSafeReference:tsr config:config keyPaths:keyPaths queue:queue];
diff --git a/Realm/RLMRealm.mm b/Realm/RLMRealm.mm
index c5e177eb2c..316ff4f58d 100644
--- a/Realm/RLMRealm.mm
+++ b/Realm/RLMRealm.mm
@@ -596,6 +596,14 @@ - (RLMRealmConfiguration *)configuration {
     return configuration;
 }
 
+- (RLMRealmConfiguration *)configurationSharingSchema {
+    RLMRealmConfiguration *configuration = [[RLMRealmConfiguration alloc] init];
+    configuration.configRef = _realm->config();
+    configuration.dynamic = _dynamic;
+    [configuration setCustomSchemaWithoutCopying:_schema];
+    return configuration;
+}
+
 - (void)beginWriteTransaction {
     [self beginWriteTransactionWithError:nil];
 }
@@ -1076,7 +1084,7 @@ - (RLMRealm *)freeze {
 
 - (RLMRealm *)thaw {
     [self verifyThread];
-    return self.isFrozen ? [RLMRealm realmWithConfiguration:self.configuration error:nil] : self;
+    return self.isFrozen ? [RLMRealm realmWithConfiguration:self.configurationSharingSchema error:nil] : self;
 }
 
 - (RLMRealm *)frozenCopy {
diff --git a/Realm/RLMRealmUtil.mm b/Realm/RLMRealmUtil.mm
index 2fad212f6e..ceb87fb967 100644
--- a/Realm/RLMRealmUtil.mm
+++ b/Realm/RLMRealmUtil.mm
@@ -234,7 +234,7 @@ @implementation RLMPinnedRealm {
 - (instancetype)initWithRealm:(RLMRealm *)realm {
     if (self = [super init]) {
         _pin = realm->_realm->duplicate();
-        _configuration = realm.configuration;
+        _configuration = realm.configurationSharingSchema;
     }
     return self;
 }
diff --git a/Realm/RLMRealm_Private.h b/Realm/RLMRealm_Private.h
index d247de39bc..e2bfa264fc 100644
--- a/Realm/RLMRealm_Private.h
+++ b/Realm/RLMRealm_Private.h
@@ -65,6 +65,11 @@ FOUNDATION_EXTERN void RLMRealmSubscribeToAll(RLMRealm *);
 @property (nonatomic, readonly, nullable) id actor;
 @property (nonatomic, readonly) bool isFlexibleSync;
 
+// `-configuration` does a deep copy of the schema as if the user mutates the
+// RLMSchema in use by a RLMRealm things will break horribly. When we know that
+// the configuration won't be exposed we can skip the copy.
+- (RLMRealmConfiguration *)configurationSharingSchema NS_RETURNS_RETAINED;
+
 + (void)resetRealmState;
 
 - (void)registerEnumerator:(RLMFastEnumerator *)enumerator;
diff --git a/Realm/RLMResults.mm b/Realm/RLMResults.mm
index 699eac7bf8..eac9566e7b 100644
--- a/Realm/RLMResults.mm
+++ b/Realm/RLMResults.mm
@@ -574,7 +574,7 @@ - (void)completionWithThreadSafeReference:(RLMThreadSafeReference * _Nullable)re
                                confinedTo:(RLMScheduler *)confinement
                                completion:(RLMResultsCompletionBlock)completion
                                     error:(NSError *_Nullable)error {
-    RLMRealmConfiguration *configuration = _realm.configuration;
+    RLMRealmConfiguration *configuration = _realm.configurationSharingSchema;
     [confinement invoke:^{
         if (error) {
             return completion(nil, error);
diff --git a/RealmSwift/Combine.swift b/RealmSwift/Combine.swift
index a55a5ee77c..4049597d45 100644
--- a/RealmSwift/Combine.swift
+++ b/RealmSwift/Combine.swift
@@ -939,7 +939,7 @@ public enum RealmPublishers {
         try? Realm(RLMRealm(configuration: config, queue: scheduler as? DispatchQueue))
     }
     static private func realm<S: Scheduler>(_ sourceRealm: Realm, _ scheduler: S) -> Realm? {
-        return realm(sourceRealm.rlmRealm.configuration, scheduler)
+        return realm(sourceRealm.rlmRealm.configurationSharingSchema(), scheduler)
     }
 
     /// A publisher which emits an asynchronously opened Realm.
@@ -1300,7 +1300,7 @@ public enum RealmPublishers {
         private let scheduler: S
 
         internal init(_ upstream: Upstream, _ scheduler: S, _ realm: Realm) {
-            self.config = realm.rlmRealm.configuration
+            self.config = realm.rlmRealm.configurationSharingSchema()
             self.upstream = upstream
             self.scheduler = scheduler
         }
@@ -1377,7 +1377,7 @@ public enum RealmPublishers {
             self.upstream
                 .map { (obj: Output) -> Handover in
                     guard let realm = obj.realm, !realm.isFrozen else { return .object(obj) }
-                    return .tsr(ThreadSafeReference(to: obj), config: realm.rlmRealm.configuration)
+                    return .tsr(ThreadSafeReference(to: obj), config: realm.rlmRealm.configurationSharingSchema())
             }
             .receive(on: scheduler)
             .compactMap { (handover: Handover) -> Output? in
diff --git a/RealmSwift/Impl/RealmCollectionImpl.swift b/RealmSwift/Impl/RealmCollectionImpl.swift
index 69d31af1a1..3249e1e38c 100644
--- a/RealmSwift/Impl/RealmCollectionImpl.swift
+++ b/RealmSwift/Impl/RealmCollectionImpl.swift
@@ -195,7 +195,7 @@ internal func with<A: Actor, Value: ThreadConfined, Return: Sendable>(
     }
 
     let tsr = ThreadSafeReference(to: value)
-    let config = Unchecked(wrappedValue: value.realm!.rlmRealm.configuration)
+    let config = Unchecked(wrappedValue: value.realm!.rlmRealm.configurationSharingSchema())
     return try await actor.invoke { actor in
         if Task.isCancelled {
             return nil