diff --git a/Source/Modules/SessionCtl_Core.swift b/Source/Modules/SessionCtl_Core.swift
index fee52c18..f433f23f 100644
--- a/Source/Modules/SessionCtl_Core.swift
+++ b/Source/Modules/SessionCtl_Core.swift
@@ -43,6 +43,10 @@ public class SessionCtl: IMKInputController {
   /// 當前副本的客體是否是輸入法本體？
   public var isServingIMEItself: Bool = false
 
+  /// 用以存儲客體的 bundleIdentifier。
+  /// 由於每次動態獲取都會耗時，所以這裡直接靜態記載之。
+  public var clientBundleIdentifier: String = ""
+
   // MARK: -
 
   /// 當前 Caps Lock 按鍵是否被摁下。
@@ -216,6 +220,7 @@ public extension SessionCtl {
       if let senderBundleID: String = (sender as? IMKTextInput)?.bundleIdentifier() {
         vCLog("activateServer(\(senderBundleID))")
         isServingIMEItself = Bundle.main.bundleIdentifier == senderBundleID
+        clientBundleIdentifier = senderBundleID
       }
     }
     DispatchQueue.main.async {
diff --git a/Source/Modules/SessionCtl_Delegates.swift b/Source/Modules/SessionCtl_Delegates.swift
index 51ede93c..ed63d513 100644
--- a/Source/Modules/SessionCtl_Delegates.swift
+++ b/Source/Modules/SessionCtl_Delegates.swift
@@ -11,11 +11,6 @@ import Shared
 // MARK: - InputHandler Delegate
 
 extension SessionCtl: InputHandlerDelegate {
-  public var clientBundleIdentifier: String {
-    guard let client = client() else { return "" }
-    return client.bundleIdentifier() ?? ""
-  }
-
   public func candidateController() -> CtlCandidateProtocol? { candidateUI }
 
   public func candidateSelectionCalledByInputHandler(at index: Int) {