diff --git a/src/tests/integration/test_performance_optimization.py b/src/tests/integration/test_performance_optimization.py
new file mode 100644
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+++ b/src/tests/integration/test_performance_optimization.py
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+"""
+Integration tests for performance optimization API endpoints.
+
+This module tests the performance-related endpoints for speed limiting, cache management,
+memory management, and download task handling.
+"""
+
+import pytest
+from fastapi.testclient import TestClient
+from unittest.mock import patch, Mock
+import time
+
+from src.server.fastapi_app import app
+
+
+@pytest.fixture
+def client():
+    """Create a test client for the FastAPI application."""
+    return TestClient(app)
+
+
+@pytest.fixture
+def auth_headers(client):
+    """Provide authentication headers for protected endpoints."""
+    # Login to get token
+    login_data = {"password": "testpassword"}
+    
+    with patch('src.server.fastapi_app.settings.master_password_hash') as mock_hash:
+        mock_hash.return_value = "5e884898da28047151d0e56f8dc6292773603d0d6aabbdd62a11ef721d1542d8"  # 'password' hash
+        response = client.post("/auth/login", json=login_data)
+    
+    if response.status_code == 200:
+        token = response.json()["access_token"]
+        return {"Authorization": f"Bearer {token}"}
+    return {}
+
+
+class TestSpeedLimitEndpoint:
+    """Test cases for /api/performance/speed-limit endpoint."""
+    
+    def test_get_speed_limit_requires_auth(self, client):
+        """Test that getting speed limit requires authentication."""
+        response = client.get("/api/performance/speed-limit")
+        assert response.status_code == 401
+    
+    def test_set_speed_limit_requires_auth(self, client):
+        """Test that setting speed limit requires authentication."""
+        response = client.post("/api/performance/speed-limit", json={"limit_mbps": 10})
+        assert response.status_code == 401
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_get_current_speed_limit(self, mock_user, client):
+        """Test getting current speed limit."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        response = client.get("/api/performance/speed-limit")
+        # Expected 404 since endpoint not implemented yet
+        assert response.status_code in [200, 404]
+        
+        if response.status_code == 200:
+            data = response.json()
+            assert "limit_mbps" in data
+            assert "current_usage_mbps" in data
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_set_speed_limit_valid(self, mock_user, client):
+        """Test setting valid speed limit."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        limit_data = {"limit_mbps": 50}
+        response = client.post("/api/performance/speed-limit", json=limit_data)
+        # Expected 404 since endpoint not implemented yet
+        assert response.status_code in [200, 404]
+    
+    def test_set_speed_limit_invalid(self, client, auth_headers):
+        """Test setting invalid speed limit."""
+        invalid_limits = [
+            {"limit_mbps": -1},  # Negative
+            {"limit_mbps": 0},   # Zero
+            {"limit_mbps": "invalid"},  # Non-numeric
+        ]
+        
+        for limit_data in invalid_limits:
+            response = client.post("/api/performance/speed-limit", json=limit_data, headers=auth_headers)
+            assert response.status_code in [400, 404, 422]
+
+
+class TestCacheStatsEndpoint:
+    """Test cases for /api/performance/cache/stats endpoint."""
+    
+    def test_cache_stats_requires_auth(self, client):
+        """Test that cache stats requires authentication."""
+        response = client.get("/api/performance/cache/stats")
+        assert response.status_code == 401
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_get_cache_stats(self, mock_user, client):
+        """Test getting cache statistics."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        response = client.get("/api/performance/cache/stats")
+        # Expected 404 since endpoint not implemented yet
+        assert response.status_code in [200, 404]
+        
+        if response.status_code == 200:
+            data = response.json()
+            expected_fields = ["hit_rate", "miss_rate", "size_bytes", "entries_count", "evictions"]
+            for field in expected_fields:
+                assert field in data
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_clear_cache(self, mock_user, client):
+        """Test clearing cache."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        response = client.delete("/api/performance/cache/stats")
+        # Expected 404 since endpoint not implemented yet
+        assert response.status_code in [200, 404]
+
+
+class TestMemoryStatsEndpoint:
+    """Test cases for /api/performance/memory/stats endpoint."""
+    
+    def test_memory_stats_requires_auth(self, client):
+        """Test that memory stats requires authentication."""
+        response = client.get("/api/performance/memory/stats")
+        assert response.status_code == 401
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_get_memory_stats(self, mock_user, client):
+        """Test getting memory statistics."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        response = client.get("/api/performance/memory/stats")
+        # Expected 404 since endpoint not implemented yet
+        assert response.status_code in [200, 404]
+        
+        if response.status_code == 200:
+            data = response.json()
+            expected_fields = ["used_bytes", "available_bytes", "percent_used", "process_memory"]
+            for field in expected_fields:
+                assert field in data
+
+
+class TestMemoryGCEndpoint:
+    """Test cases for /api/performance/memory/gc endpoint."""
+    
+    def test_memory_gc_requires_auth(self, client):
+        """Test that memory garbage collection requires authentication."""
+        response = client.post("/api/performance/memory/gc")
+        assert response.status_code == 401
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_trigger_garbage_collection(self, mock_user, client):
+        """Test triggering garbage collection."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        response = client.post("/api/performance/memory/gc")
+        # Expected 404 since endpoint not implemented yet
+        assert response.status_code in [200, 404]
+        
+        if response.status_code == 200:
+            data = response.json()
+            assert "collected_objects" in data
+            assert "memory_freed_bytes" in data
+
+
+class TestDownloadTasksEndpoint:
+    """Test cases for /api/performance/downloads/tasks endpoint."""
+    
+    def test_download_tasks_requires_auth(self, client):
+        """Test that download tasks requires authentication."""
+        response = client.get("/api/performance/downloads/tasks")
+        assert response.status_code == 401
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_get_download_tasks(self, mock_user, client):
+        """Test getting download tasks."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        response = client.get("/api/performance/downloads/tasks")
+        # Expected 404 since endpoint not implemented yet
+        assert response.status_code in [200, 404]
+        
+        if response.status_code == 200:
+            data = response.json()
+            assert "tasks" in data
+            assert isinstance(data["tasks"], list)
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_get_download_tasks_with_status_filter(self, mock_user, client):
+        """Test getting download tasks with status filter."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        response = client.get("/api/performance/downloads/tasks?status=active")
+        assert response.status_code in [200, 404]
+        
+        response = client.get("/api/performance/downloads/tasks?status=completed")
+        assert response.status_code in [200, 404]
+
+
+class TestAddDownloadTaskEndpoint:
+    """Test cases for /api/performance/downloads/add-task endpoint."""
+    
+    def test_add_download_task_requires_auth(self, client):
+        """Test that adding download task requires authentication."""
+        response = client.post("/api/performance/downloads/add-task", json={"anime_id": "test"})
+        assert response.status_code == 401
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_add_download_task_valid(self, mock_user, client):
+        """Test adding valid download task."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        task_data = {
+            "anime_id": "anime123",
+            "episode_range": {"start": 1, "end": 12},
+            "quality": "1080p",
+            "priority": "normal"
+        }
+        
+        response = client.post("/api/performance/downloads/add-task", json=task_data)
+        # Expected 404 since endpoint not implemented yet
+        assert response.status_code in [200, 404]
+        
+        if response.status_code == 200:
+            data = response.json()
+            assert "task_id" in data
+            assert "status" in data
+    
+    def test_add_download_task_invalid(self, client, auth_headers):
+        """Test adding invalid download task."""
+        invalid_tasks = [
+            {},  # Empty data
+            {"anime_id": ""},  # Empty anime_id
+            {"anime_id": "test", "episode_range": {"start": 5, "end": 2}},  # Invalid range
+        ]
+        
+        for task_data in invalid_tasks:
+            response = client.post("/api/performance/downloads/add-task", json=task_data, headers=auth_headers)
+            assert response.status_code in [400, 404, 422]
+
+
+class TestResumeTasksEndpoint:
+    """Test cases for /api/performance/resume/tasks endpoint."""
+    
+    def test_resume_tasks_requires_auth(self, client):
+        """Test that resuming tasks requires authentication."""
+        response = client.post("/api/performance/resume/tasks")
+        assert response.status_code == 401
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_resume_all_tasks(self, mock_user, client):
+        """Test resuming all paused tasks."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        response = client.post("/api/performance/resume/tasks")
+        # Expected 404 since endpoint not implemented yet
+        assert response.status_code in [200, 404]
+        
+        if response.status_code == 200:
+            data = response.json()
+            assert "resumed_count" in data
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_resume_specific_task(self, mock_user, client):
+        """Test resuming specific task."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        task_data = {"task_id": "task123"}
+        response = client.post("/api/performance/resume/tasks", json=task_data)
+        assert response.status_code in [200, 404]
+
+
+class TestPerformanceEndpointsIntegration:
+    """Integration tests for performance endpoints."""
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_performance_workflow(self, mock_user, client):
+        """Test typical performance monitoring workflow."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        # 1. Check current memory stats
+        response = client.get("/api/performance/memory/stats")
+        assert response.status_code in [200, 404]
+        
+        # 2. Check cache stats
+        response = client.get("/api/performance/cache/stats")
+        assert response.status_code in [200, 404]
+        
+        # 3. Check download tasks
+        response = client.get("/api/performance/downloads/tasks")
+        assert response.status_code in [200, 404]
+        
+        # 4. If needed, trigger garbage collection
+        response = client.post("/api/performance/memory/gc")
+        assert response.status_code in [200, 404]
+    
+    def test_performance_endpoints_error_handling(self, client, auth_headers):
+        """Test error handling across performance endpoints."""
+        # Test various endpoints with malformed requests
+        endpoints_methods = [
+            ("GET", "/api/performance/memory/stats"),
+            ("GET", "/api/performance/cache/stats"),
+            ("GET", "/api/performance/downloads/tasks"),
+            ("POST", "/api/performance/memory/gc"),
+            ("POST", "/api/performance/resume/tasks"),
+        ]
+        
+        for method, endpoint in endpoints_methods:
+            if method == "GET":
+                response = client.get(endpoint, headers=auth_headers)
+            else:
+                response = client.post(endpoint, headers=auth_headers)
+            
+            # Should either work (200) or not be implemented yet (404)
+            assert response.status_code in [200, 404]
+    
+    @patch('src.server.fastapi_app.get_current_user')
+    def test_concurrent_performance_requests(self, mock_user, client):
+        """Test handling of concurrent performance requests."""
+        mock_user.return_value = {"user_id": "test_user"}
+        
+        # This would test actual concurrency in a real implementation
+        # For now, just verify endpoints are accessible
+        response = client.get("/api/performance/memory/stats")
+        assert response.status_code in [200, 404]
+
+
+if __name__ == "__main__":
+    pytest.main([__file__, "-v"])
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