diff --git a/server/TracyWorker.cpp b/server/TracyWorker.cpp
index 6ff98f84..28e7c121 100644
--- a/server/TracyWorker.cpp
+++ b/server/TracyWorker.cpp
@@ -8949,7 +8949,19 @@ static bool IsFrameExternalImpl( const char* filename, const char* image )
 
 bool Worker::IsFrameExternal( StringIdx filename, StringIdx image )
 {
-    return IsFrameExternalImpl( GetString( filename ), image.Active() ? GetString( image ) : nullptr );
+    const auto key = ( uint64_t( filename.Raw() ) << 32 ) | image.Raw();
+
+    {
+        std::shared_lock lock( m_isExternalCacheLock );
+        auto it = m_isExternalCache.find( key );
+        if( it != m_isExternalCache.end() ) return it->second;
+    }
+
+    const auto res = IsFrameExternalImpl( GetString( filename ), image.Active() ? GetString( image ) : nullptr );
+
+    std::lock_guard lock( m_isExternalCacheLock );
+    m_isExternalCache.emplace( key, res );
+    return res;
 }
 
 }
diff --git a/server/TracyWorker.hpp b/server/TracyWorker.hpp
index 1922ab27..653de169 100644
--- a/server/TracyWorker.hpp
+++ b/server/TracyWorker.hpp
@@ -1150,6 +1150,9 @@ private:
     Vector<InlineStackData> m_inlineStack;
 
     std::vector<uint32_t> m_pendingThreadHints;
+
+    unordered_flat_map<uint64_t, bool> m_isExternalCache;
+    std::shared_mutex m_isExternalCacheLock;
 };
 
 }