diff --git a/Source/Engine/McBopomofoLM.cpp b/Source/Engine/McBopomofoLM.cpp
index 8c32d0d4..6e5cb650 100644
--- a/Source/Engine/McBopomofoLM.cpp
+++ b/Source/Engine/McBopomofoLM.cpp
@@ -39,6 +39,11 @@ McBopomofoLM::~McBopomofoLM()
     m_phraseReplacement.close();
 }
 
+bool McBopomofoLM::isDataModelLoaded()
+{
+    return m_languageModel.isLoaded();
+}
+
 void McBopomofoLM::loadLanguageModel(const char* languageModelDataPath)
 {
     if (languageModelDataPath) {
diff --git a/Source/Engine/McBopomofoLM.h b/Source/Engine/McBopomofoLM.h
index b70723f9..1636c55d 100644
--- a/Source/Engine/McBopomofoLM.h
+++ b/Source/Engine/McBopomofoLM.h
@@ -64,6 +64,8 @@ public:
     /// Asks to load the primary language model a the given path.
     /// @param languageModelPath Thw path of the language model.
     void loadLanguageModel(const char* languageModelPath);
+    /// If the data model is already loaded.
+    bool isDataModelLoaded();
     /// Asks to load the user phrases and excluded phrases at the given path.
     /// @param userPhrasesPath The path of user phrases.
     /// @param excludedPhrasesPath The path of excluded phrases.
diff --git a/Source/Engine/ParselessLM.cpp b/Source/Engine/ParselessLM.cpp
index c0de5c00..2efe9701 100644
--- a/Source/Engine/ParselessLM.cpp
+++ b/Source/Engine/ParselessLM.cpp
@@ -32,6 +32,14 @@
 
 McBopomofo::ParselessLM::~ParselessLM() { close(); }
 
+bool McBopomofo::ParselessLM::isLoaded()
+{
+    if (data_) {
+        return true;
+    }
+    return false;
+}
+
 bool McBopomofo::ParselessLM::open(const std::string_view& path)
 {
     if (data_) {
diff --git a/Source/Engine/ParselessLM.h b/Source/Engine/ParselessLM.h
index 8d2c0b88..e3b4632a 100644
--- a/Source/Engine/ParselessLM.h
+++ b/Source/Engine/ParselessLM.h
@@ -37,6 +37,7 @@ class ParselessLM : public Formosa::Gramambular::LanguageModel {
 public:
     ~ParselessLM() override;
 
+    bool isLoaded();
     bool open(const std::string_view& path);
     void close();
 
diff --git a/Source/LanguageModelManager.mm b/Source/LanguageModelManager.mm
index 87b46cf9..06c11c12 100644
--- a/Source/LanguageModelManager.mm
+++ b/Source/LanguageModelManager.mm
@@ -55,17 +55,25 @@ static void LTLoadLanguageModelFile(NSString *filenameWithoutExtension, McBopomo
 
 + (void)loadDataModels
 {
-    LTLoadLanguageModelFile(@"data", gLanguageModelMcBopomofo);
-    LTLoadLanguageModelFile(@"data-plain-bpmf", gLanguageModelPlainBopomofo);
+    if (!gLanguageModelMcBopomofo.isDataModelLoaded()) {
+        LTLoadLanguageModelFile(@"data", gLanguageModelMcBopomofo);
+    }
+    if (!gLanguageModelPlainBopomofo.isDataModelLoaded()) {
+        LTLoadLanguageModelFile(@"data-plain-bpmf", gLanguageModelPlainBopomofo);
+    }
 }
 
 + (void)loadDataModel:(InputMode)mode
 {
     if ([mode isEqualToString:InputModeBopomofo]) {
-        LTLoadLanguageModelFile(@"data", gLanguageModelMcBopomofo);
+        if (!gLanguageModelMcBopomofo.isDataModelLoaded()) {
+            LTLoadLanguageModelFile(@"data", gLanguageModelMcBopomofo);
+        }
     }
     if ([mode isEqualToString:InputModePlainBopomofo]) {
-        LTLoadLanguageModelFile(@"data-plain-bpmf", gLanguageModelPlainBopomofo);
+        if (!gLanguageModelPlainBopomofo.isDataModelLoaded()) {
+            LTLoadLanguageModelFile(@"data-plain-bpmf", gLanguageModelPlainBopomofo);
+        }
     }
 }