diff --git a/app.go b/app.go
index f7c0ad6..fe1ce99 100644
--- a/app.go
+++ b/app.go
@@ -38,6 +38,7 @@ type App struct {
 	pdfAPI        *api.PdfAPI
 	filesystem    *filesystem.FileSystemService
 	sftpService   *sftp.Service
+	profileSvc    *service.ProfileService
 	isAlwaysOnTop bool
 	mu            sync.Mutex
 }
@@ -986,13 +987,13 @@ type SaveProfileRequest struct {
 	LastConnected *int64     `json:"last_connected"`
 }
 
-var profileSvc *service.ProfileService
-
 func (a *App) ensureProfileSvc() *service.ProfileService {
-	if profileSvc == nil {
-		profileSvc = service.NewProfileService()
+	a.mu.Lock()
+	defer a.mu.Unlock()
+	if a.profileSvc == nil {
+		a.profileSvc = service.NewProfileService()
 	}
-	return profileSvc
+	return a.profileSvc
 }
 
 func (a *App) LoadConnectionProfiles() ([]map[string]interface{}, error) {
diff --git a/frontend/src/api/connection-manager.ts b/frontend/src/api/connection-manager.ts
index d480679..4bb7ecf 100644
--- a/frontend/src/api/connection-manager.ts
+++ b/frontend/src/api/connection-manager.ts
@@ -327,7 +327,6 @@ class ConnectionManagerImpl {
 
     if (profile.type === 'sftp') {
       if (!profile.password && !profile.keyPath) {
-        this._pool.set(profileId, new WailsTransport())
         this.setState('error')
         return
       }
diff --git a/internal/sftp/client.go b/internal/sftp/client.go
index 1c16911..d17ef67 100644
--- a/internal/sftp/client.go
+++ b/internal/sftp/client.go
@@ -22,6 +22,7 @@ type Client struct {
 // Manager 全局 SFTP 连接管理器（以 host:port 为 key 的连接池）
 type Manager struct {
 	clients sync.Map // map[string]*Client
+	mu      sync.Mutex
 }
 
 var globalManager = &Manager{}
@@ -35,6 +36,9 @@ func GetManager() *Manager {
 func (m *Manager) Connect(config *Config) (*Client, error) {
 	key := fmt.Sprintf("%s:%d", config.Host, config.Port)
 
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
 	if existing, ok := m.clients.Load(key); ok {
 		c := existing.(*Client)
 		if c.IsHealthy() {
diff --git a/internal/sftp/service.go b/internal/sftp/service.go
index 2f29b49..9eefaed 100644
--- a/internal/sftp/service.go
+++ b/internal/sftp/service.go
@@ -279,8 +279,12 @@ func (s *Service) DownloadToTemp(connID string, remotePath string) (string, erro
 	}
 
 	tmpDir := os.TempDir()
-	// 用时间戳+随机数避免同名文件覆盖
-	localPath := filepath.Join(tmpDir, fmt.Sprintf("udesk-sftp-preview-%d-%s", time.Now().UnixNano(), filepath.Base(remotePath)))
+	tmpFile, e := os.CreateTemp(tmpDir, "udesk-sftp-*-"+filepath.Base(remotePath))
+	if e != nil {
+		return "", fmt.Errorf("创建临时文件失败: %w", e)
+	}
+	localPath := tmpFile.Name()
+	tmpFile.Close()
 
 	err = c.WithRetry(func(sc *sftpclient.Client) error {
 		src, e := sc.Open(remotePath)
diff --git a/internal/storage/sqlite.go b/internal/storage/sqlite.go
index 34cc12d..ecb699b 100644
--- a/internal/storage/sqlite.go
+++ b/internal/storage/sqlite.go
@@ -2,11 +2,12 @@ package storage
 
 import (
 	"fmt"
-	"u-desk/internal/common"
-	"u-desk/internal/storage/models"
 	"os"
 	"path/filepath"
+	"sync"
 	"time"
+	"u-desk/internal/common"
+	"u-desk/internal/storage/models"
 
 	"github.com/glebarez/sqlite"
 	"gorm.io/gorm"
@@ -14,61 +15,53 @@ import (
 )
 
 var globalDB *gorm.DB
+var initOnce sync.Once
 
-// Init 快速初始化 SQLite（兼容旧代码）
 func Init() (*gorm.DB, error) {
 	return InitFast()
 }
 
-// InitFast 超快速初始化 SQLite（优化版）
-// 跳过不必要的检查，使用 WAL 模式，优化连接池
 func InitFast() (*gorm.DB, error) {
 	if globalDB != nil {
 		return globalDB, nil
 	}
+	var initErr error
+	initOnce.Do(func() {
+		dataDir := common.GetUserDataDir()
+		if e := os.MkdirAll(dataDir, 0755); e != nil {
+			initErr = e
+			return
+		}
 
-	// 使用统一的数据目录
-	dataDir := common.GetUserDataDir()
-	if err := os.MkdirAll(dataDir, 0755); err != nil {
-		return nil, err
-	}
+		dbPath := filepath.Join(dataDir, "app.db")
+		db, e := gorm.Open(sqlite.Open(dbPath+"?_pragma=journal_mode(WAL)&_pragma=synchronous(NORMAL)&_pragma=cache_size(-64000)&_pragma=temp_store(MEMORY)&_pragma=mmap_size(30000000000)&_pragma=page_size(4096)&_pragma=foreign_keys(1)"), &gorm.Config{
+			Logger:                 logger.Default.LogMode(logger.Silent),
+			SkipDefaultTransaction: true,
+			PrepareStmt:            true,
+		})
+		if e != nil {
+			initErr = e
+			return
+		}
 
-	dbPath := filepath.Join(dataDir, "app.db")
+		sqlDB, e := db.DB()
+		if e != nil {
+			initErr = fmt.Errorf("获取底层SQL数据库失败: %v", e)
+			return
+		}
+		sqlDB.SetMaxOpenConns(1)
+		sqlDB.SetMaxIdleConns(1)
+		sqlDB.SetConnMaxLifetime(time.Hour)
 
-	// 极限性能优化参数：
-	// - journal_mode=WAL: 写前日志，大幅提升并发性能
-	// - synchronous=NORMAL: 降低持久性要求，提升性能
-	// - cache_size=-64000: 64MB 缓存，减少磁盘 I/O
-	// - temp_store=MEMORY: 临时表存储在内存中
-	// - mmap_size=30000000000: 300MB 内存映射，加速读取
-	// - page_size=4096: 优化页面大小
-	db, err := gorm.Open(sqlite.Open(dbPath+"?_pragma=journal_mode(WAL)&_pragma=synchronous(NORMAL)&_pragma=cache_size(-64000)&_pragma=temp_store(MEMORY)&_pragma=mmap_size(30000000000)&_pragma=page_size(4096)&_pragma=foreign_keys(1)"), &gorm.Config{
-		Logger: logger.Default.LogMode(logger.Silent),
-		SkipDefaultTransaction: true, // 跳过默认事务，提升性能
-		PrepareStmt: true,            // 预编译语句缓存
+		if e := db.AutoMigrate(&models.AppConfig{}, &models.ConnectionProfile{}); e != nil {
+			initErr = e
+			return
+		}
+		globalDB = db
 	})
-	if err != nil {
-		return nil, err
+	if initErr != nil {
+		return nil, initErr
 	}
-
-	sqlDB, err := db.DB()
-	if err != nil {
-		return nil, fmt.Errorf("获取底层SQL数据库失败: %v", err)
-	}
-	sqlDB.SetMaxOpenConns(1) // SQLite 只需要一个连接
-	sqlDB.SetMaxIdleConns(1)
-	sqlDB.SetConnMaxLifetime(time.Hour)
-
-	// AutoMigrate 在启动时执行，但只在表结构不存在时创建
-	// SQLite 的 AutoMigrate 很快，不会造成明显延迟
-	if err := db.AutoMigrate(
-		&models.AppConfig{},
-		&models.ConnectionProfile{},
-	); err != nil {
-		return nil, err
-	}
-
-	globalDB = db
 	return globalDB, nil
 }