diff --git a/src/Sql/dbo/Stored Procedures/Collection_UpdateWithGroupsAndUsers.sql b/src/Sql/dbo/Stored Procedures/Collection_UpdateWithGroupsAndUsers.sql
index da7e77cc14..4a66b20d86 100644
--- a/src/Sql/dbo/Stored Procedures/Collection_UpdateWithGroupsAndUsers.sql	
+++ b/src/Sql/dbo/Stored Procedures/Collection_UpdateWithGroupsAndUsers.sql	
@@ -14,98 +14,88 @@ BEGIN
     EXEC [dbo].[Collection_Update] @Id, @OrganizationId, @Name, @ExternalId, @CreationDate, @RevisionDate
 
     -- Groups
-    ;WITH [AvailableGroupsCTE] AS(
-        SELECT
-            Id
-        FROM
-            [dbo].[Group]
-        WHERE
-            OrganizationId = @OrganizationId
+    -- Delete groups that are no longer in source
+    DELETE cg
+    FROM [dbo].[CollectionGroup] cg
+             LEFT JOIN @Groups g ON cg.GroupId = g.Id
+    WHERE cg.CollectionId = @Id
+      AND g.Id IS NULL;
+
+    -- Update existing groups
+    UPDATE cg
+    SET cg.ReadOnly = g.ReadOnly,
+        cg.HidePasswords = g.HidePasswords,
+        cg.Manage = g.Manage
+    FROM [dbo].[CollectionGroup] cg
+             INNER JOIN @Groups g ON cg.GroupId = g.Id
+    WHERE cg.CollectionId = @Id
+      AND (cg.ReadOnly != g.ReadOnly
+        OR cg.HidePasswords != g.HidePasswords
+        OR cg.Manage != g.Manage);
+
+    -- Insert new groups
+    INSERT INTO [dbo].[CollectionGroup]
+    (
+        [CollectionId],
+        [GroupId],
+        [ReadOnly],
+        [HidePasswords],
+        [Manage]
     )
-    MERGE
-        [dbo].[CollectionGroup] AS [Target]
-    USING
-        @Groups AS [Source]
-    ON
-        [Target].[CollectionId] = @Id
-        AND [Target].[GroupId] = [Source].[Id]
-    WHEN NOT MATCHED BY TARGET
-    AND [Source].[Id] IN (SELECT [Id] FROM [AvailableGroupsCTE]) THEN
-        INSERT -- Add explicit column list
-        (
-	        [CollectionId],
-	        [GroupId],
-	        [ReadOnly],
-	        [HidePasswords],
-            [Manage]
-    	)
-        VALUES
-        (
-            @Id,
-            [Source].[Id],
-            [Source].[ReadOnly],
-            [Source].[HidePasswords],
-            [Source].[Manage]
-        )
-    WHEN MATCHED AND (
-        [Target].[ReadOnly] != [Source].[ReadOnly]
-        OR [Target].[HidePasswords] != [Source].[HidePasswords]
-        OR [Target].[Manage] != [Source].[Manage]
-    ) THEN
-        UPDATE SET [Target].[ReadOnly] = [Source].[ReadOnly],
-                   [Target].[HidePasswords] = [Source].[HidePasswords],
-                   [Target].[Manage] = [Source].[Manage]
-    WHEN NOT MATCHED BY SOURCE
-    AND [Target].[CollectionId] = @Id THEN
-        DELETE
-    ;
+    SELECT
+        @Id,
+        g.Id,
+        g.ReadOnly,
+        g.HidePasswords,
+        g.Manage
+    FROM @Groups g
+             INNER JOIN [dbo].[Group] grp ON grp.Id = g.Id
+             LEFT JOIN [dbo].[CollectionGroup] cg
+                       ON cg.CollectionId = @Id AND cg.GroupId = g.Id
+    WHERE grp.OrganizationId = @OrganizationId
+      AND cg.CollectionId IS NULL;
 
     -- Users
-    ;WITH [AvailableGroupsCTE] AS(
-        SELECT
-            Id
-        FROM
-            [dbo].[OrganizationUser]
-        WHERE
-            OrganizationId = @OrganizationId
+    -- Delete users that are no longer in source
+    DELETE cu
+    FROM [dbo].[CollectionUser] cu
+             LEFT JOIN @Users u ON cu.OrganizationUserId = u.Id
+    WHERE cu.CollectionId = @Id
+      AND u.Id IS NULL;
+
+    -- Update existing users
+    UPDATE cu
+    SET cu.ReadOnly = u.ReadOnly,
+        cu.HidePasswords = u.HidePasswords,
+        cu.Manage = u.Manage
+    FROM [dbo].[CollectionUser] cu
+             INNER JOIN @Users u ON cu.OrganizationUserId = u.Id
+    WHERE cu.CollectionId = @Id
+      AND (cu.ReadOnly != u.ReadOnly
+        OR cu.HidePasswords != u.HidePasswords
+        OR cu.Manage != u.Manage);
+
+    -- Insert new users
+    INSERT INTO [dbo].[CollectionUser]
+    (
+        [CollectionId],
+        [OrganizationUserId],
+        [ReadOnly],
+        [HidePasswords],
+        [Manage]
     )
-    MERGE
-        [dbo].[CollectionUser] AS [Target]
-    USING
-        @Users AS [Source]
-    ON
-        [Target].[CollectionId] = @Id
-        AND [Target].[OrganizationUserId] = [Source].[Id]
-    WHEN NOT MATCHED BY TARGET
-    AND [Source].[Id] IN (SELECT [Id] FROM [AvailableGroupsCTE]) THEN
-        INSERT
-        (
-	        [CollectionId],
-	        [OrganizationUserId],
-	        [ReadOnly],
-	        [HidePasswords],
-            [Manage]
-    	)
-        VALUES
-        (
-            @Id,
-            [Source].[Id],
-            [Source].[ReadOnly],
-            [Source].[HidePasswords],
-            [Source].[Manage]
-        )
-    WHEN MATCHED AND (
-        [Target].[ReadOnly] != [Source].[ReadOnly]
-        OR [Target].[HidePasswords] != [Source].[HidePasswords]
-        OR [Target].[Manage] != [Source].[Manage]
-    ) THEN
-        UPDATE SET [Target].[ReadOnly] = [Source].[ReadOnly],
-                   [Target].[HidePasswords] = [Source].[HidePasswords],
-                   [Target].[Manage] = [Source].[Manage]
-    WHEN NOT MATCHED BY SOURCE
-    AND [Target].[CollectionId] = @Id THEN
-        DELETE
-    ;
+    SELECT
+        @Id,
+        u.Id,
+        u.ReadOnly,
+        u.HidePasswords,
+        u.Manage
+    FROM @Users u
+             INNER JOIN [dbo].[OrganizationUser] ou ON ou.Id = u.Id
+             LEFT JOIN [dbo].[CollectionUser] cu
+                       ON cu.CollectionId = @Id AND cu.OrganizationUserId = u.Id
+    WHERE ou.OrganizationId = @OrganizationId
+      AND cu.CollectionId IS NULL;
 
     EXEC [dbo].[User_BumpAccountRevisionDateByCollectionId] @Id, @OrganizationId
 END
diff --git a/src/Sql/dbo/Tables/CollectionGroup.sql b/src/Sql/dbo/Tables/CollectionGroup.sql
index 756cd79ece..72a6710e2a 100644
--- a/src/Sql/dbo/Tables/CollectionGroup.sql
+++ b/src/Sql/dbo/Tables/CollectionGroup.sql
@@ -9,3 +9,9 @@
     CONSTRAINT [FK_CollectionGroup_Group] FOREIGN KEY ([GroupId]) REFERENCES [dbo].[Group] ([Id]) ON DELETE CASCADE
 );
 
+GO
+CREATE NONCLUSTERED INDEX IX_CollectionGroup_GroupId
+    ON [dbo].[CollectionGroup] (GroupId)
+    INCLUDE (ReadOnly, HidePasswords, Manage)
+
+GO
diff --git a/src/Sql/dbo/Tables/CollectionUser.sql b/src/Sql/dbo/Tables/CollectionUser.sql
index 8e0c0ef035..afdb0f84a0 100644
--- a/src/Sql/dbo/Tables/CollectionUser.sql
+++ b/src/Sql/dbo/Tables/CollectionUser.sql
@@ -9,3 +9,9 @@
     CONSTRAINT [FK_CollectionUser_OrganizationUser] FOREIGN KEY ([OrganizationUserId]) REFERENCES [dbo].[OrganizationUser] ([Id])
 );
 
+GO
+CREATE NONCLUSTERED INDEX IX_CollectionUser_OrganizationUserId
+    ON [dbo].[CollectionUser] (OrganizationUserId)
+    INCLUDE (ReadOnly, HidePasswords, Manage)
+
+GO
diff --git a/test/Infrastructure.IntegrationTest/Vault/Repositories/CollectionRepositoryTests.cs b/test/Infrastructure.IntegrationTest/Vault/Repositories/CollectionRepositoryTests.cs
index fa7197ff61..268d46ef6b 100644
--- a/test/Infrastructure.IntegrationTest/Vault/Repositories/CollectionRepositoryTests.cs
+++ b/test/Infrastructure.IntegrationTest/Vault/Repositories/CollectionRepositoryTests.cs
@@ -599,5 +599,11 @@ public class CollectionRepositoryTests
         Assert.True(actualOrgUser3.Manage);
         Assert.False(actualOrgUser3.HidePasswords);
         Assert.True(actualOrgUser3.ReadOnly);
+
+        // Clean up data
+        await userRepository.DeleteAsync(user);
+        await organizationRepository.DeleteAsync(organization);
+        await groupRepository.DeleteManyAsync([group1.Id, group2.Id, group3.Id]);
+        await organizationUserRepository.DeleteManyAsync([orgUser1.Id, orgUser2.Id, orgUser3.Id]);
     }
 }
diff --git a/util/Migrator/DbScripts/2025-04-07_00_Collections_UpdateWithGroupsAndUsers_AndIndices.sql b/util/Migrator/DbScripts/2025-04-07_00_Collections_UpdateWithGroupsAndUsers_AndIndices.sql
new file mode 100644
index 0000000000..5bdeb5b254
--- /dev/null
+++ b/util/Migrator/DbScripts/2025-04-07_00_Collections_UpdateWithGroupsAndUsers_AndIndices.sql
@@ -0,0 +1,118 @@
+CREATE OR ALTER PROCEDURE [dbo].[Collection_UpdateWithGroupsAndUsers]
+    @Id UNIQUEIDENTIFIER,
+    @OrganizationId UNIQUEIDENTIFIER,
+    @Name VARCHAR(MAX),
+    @ExternalId NVARCHAR(300),
+    @CreationDate DATETIME2(7),
+    @RevisionDate DATETIME2(7),
+    @Groups AS [dbo].[CollectionAccessSelectionType] READONLY,
+    @Users AS [dbo].[CollectionAccessSelectionType] READONLY
+AS
+BEGIN
+    SET NOCOUNT ON
+
+    EXEC [dbo].[Collection_Update] @Id, @OrganizationId, @Name, @ExternalId, @CreationDate, @RevisionDate
+
+    -- Groups
+    -- Delete groups that are no longer in source
+    DELETE cg
+    FROM [dbo].[CollectionGroup] cg
+    LEFT JOIN @Groups g ON cg.GroupId = g.Id
+    WHERE cg.CollectionId = @Id
+    AND g.Id IS NULL;
+
+    -- Update existing groups
+    UPDATE cg
+    SET cg.ReadOnly = g.ReadOnly,
+        cg.HidePasswords = g.HidePasswords,
+        cg.Manage = g.Manage
+    FROM [dbo].[CollectionGroup] cg
+    INNER JOIN @Groups g ON cg.GroupId = g.Id
+    WHERE cg.CollectionId = @Id
+    AND (cg.ReadOnly != g.ReadOnly
+         OR cg.HidePasswords != g.HidePasswords
+         OR cg.Manage != g.Manage);
+
+    -- Insert new groups
+    INSERT INTO [dbo].[CollectionGroup]
+    (
+        [CollectionId],
+        [GroupId],
+        [ReadOnly],
+        [HidePasswords],
+        [Manage]
+    )
+    SELECT
+        @Id,
+        g.Id,
+        g.ReadOnly,
+        g.HidePasswords,
+        g.Manage
+    FROM @Groups g
+    INNER JOIN [dbo].[Group] grp ON grp.Id = g.Id
+    LEFT JOIN [dbo].[CollectionGroup] cg
+        ON cg.CollectionId = @Id AND cg.GroupId = g.Id
+    WHERE grp.OrganizationId = @OrganizationId
+    AND cg.CollectionId IS NULL;
+
+    -- Users
+    -- Delete users that are no longer in source
+    DELETE cu
+    FROM [dbo].[CollectionUser] cu
+    LEFT JOIN @Users u ON cu.OrganizationUserId = u.Id
+    WHERE cu.CollectionId = @Id
+    AND u.Id IS NULL;
+
+    -- Update existing users
+    UPDATE cu
+    SET cu.ReadOnly = u.ReadOnly,
+        cu.HidePasswords = u.HidePasswords,
+        cu.Manage = u.Manage
+    FROM [dbo].[CollectionUser] cu
+    INNER JOIN @Users u ON cu.OrganizationUserId = u.Id
+    WHERE cu.CollectionId = @Id
+    AND (cu.ReadOnly != u.ReadOnly
+         OR cu.HidePasswords != u.HidePasswords
+         OR cu.Manage != u.Manage);
+
+    -- Insert new users
+    INSERT INTO [dbo].[CollectionUser]
+    (
+        [CollectionId],
+        [OrganizationUserId],
+        [ReadOnly],
+        [HidePasswords],
+        [Manage]
+    )
+    SELECT
+        @Id,
+        u.Id,
+        u.ReadOnly,
+        u.HidePasswords,
+        u.Manage
+    FROM @Users u
+    INNER JOIN [dbo].[OrganizationUser] ou ON ou.Id = u.Id
+    LEFT JOIN [dbo].[CollectionUser] cu
+        ON cu.CollectionId = @Id AND cu.OrganizationUserId = u.Id
+    WHERE ou.OrganizationId = @OrganizationId
+    AND cu.CollectionId IS NULL;
+
+    EXEC [dbo].[User_BumpAccountRevisionDateByCollectionId] @Id, @OrganizationId
+END
+GO
+
+IF NOT EXISTS(SELECT name FROM sys.indexes WHERE name = 'IX_CollectionGroup_GroupId')
+    BEGIN
+        CREATE NONCLUSTERED INDEX IX_CollectionGroup_GroupId
+            ON [dbo].[CollectionGroup] (GroupId)
+            INCLUDE (ReadOnly, HidePasswords, Manage)
+    END
+GO
+
+IF NOT EXISTS(SELECT name FROM sys.indexes WHERE name = 'IX_CollectionUser_OrganizationUserId')
+    BEGIN
+        CREATE NONCLUSTERED INDEX IX_CollectionUser_OrganizationUserId
+            ON [dbo].[CollectionUser] (OrganizationUserId)
+            INCLUDE (ReadOnly, HidePasswords, Manage)
+    END
+GO