diff --git a/Tracking/Acts/ActsPatternRecognition/CMakeLists.txt b/Tracking/Acts/ActsPatternRecognition/CMakeLists.txt
index 158fec695ee7eb7ca07a53d32f2ab6fc5f169d6b..53c15d9f76f29d288f9c15f184a11cb288175843 100644
--- a/Tracking/Acts/ActsPatternRecognition/CMakeLists.txt
+++ b/Tracking/Acts/ActsPatternRecognition/CMakeLists.txt
@@ -1,4 +1,4 @@
-# Copyright (C) 2002-2023 CERN for the benefit of the ATLAS collaboration
+# Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
 
 # Declare the package name:
 atlas_subdir( ActsPatternRecognition )
@@ -36,3 +36,14 @@ atlas_add_component( ActsPatternRecognition
 		       xAODInDetMeasurement )
 
 atlas_install_data( share/*.txt )
+
+
+if ( "${CMAKE_BUILD_TYPE}" STREQUAL "Debug" )
+  set_source_files_properties(
+     ${CMAKE_CURRENT_SOURCE_DIR}/src/SeedingTool.cxx
+     ${CMAKE_CURRENT_SOURCE_DIR}/src/GbtsSeedingTool.cxx
+     ${CMAKE_CURRENT_SOURCE_DIR}/src/OrthogonalSeedingTool.cxx
+     PROPERTIES
+     COMPILE_FLAGS "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} -UNDEBUG -fvisibility-inlines-hidden "
+     COMPILE_DEFINITIONS "FLATTEN" )
+endif()
diff --git a/Tracking/Acts/ActsPatternRecognition/src/GbtsSeedingTool.cxx b/Tracking/Acts/ActsPatternRecognition/src/GbtsSeedingTool.cxx
index 659770042412865ec927d66fd0f7fdc942af1822..c656d7f64f8494406387218dc960fc148019b867 100644
--- a/Tracking/Acts/ActsPatternRecognition/src/GbtsSeedingTool.cxx
+++ b/Tracking/Acts/ActsPatternRecognition/src/GbtsSeedingTool.cxx
@@ -1,8 +1,14 @@
 /*
-  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
 */
 
+#if defined(FLATTEN) && defined(__GNUC__)
+// Avoid warning in dbg build
+#pragma GCC optimize "-fno-var-tracking-assignments"
+#endif
+
 #include "src/GbtsSeedingTool.h"
+#include "CxxUtils/inline_hints.h"
 
 namespace ActsTrk {
 
@@ -43,6 +49,7 @@ namespace ActsTrk {
     return StatusCode::SUCCESS;
   }
 
+  ATH_FLATTEN
   StatusCode
   GbtsSeedingTool::createSeeds(const EventContext& ctx,
 			       const Acts::SpacePointContainer<ActsTrk::SpacePointCollector, Acts::detail::RefHolder>& spContainer,
diff --git a/Tracking/Acts/ActsPatternRecognition/src/OrthogonalSeedingTool.cxx b/Tracking/Acts/ActsPatternRecognition/src/OrthogonalSeedingTool.cxx
index 9ed069765e96bfdbfd12b6df862d4a3c6dad5bbf..170fd51e47d5cf00e2cf2ceeabb0966a01111562 100644
--- a/Tracking/Acts/ActsPatternRecognition/src/OrthogonalSeedingTool.cxx
+++ b/Tracking/Acts/ActsPatternRecognition/src/OrthogonalSeedingTool.cxx
@@ -1,8 +1,14 @@
 /*
-  Copyright (C) 2002-2023 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
 */
 
+#if defined(FLATTEN) && defined(__GNUC__)
+// Avoid warning in dbg build
+#pragma GCC optimize "-fno-var-tracking-assignments"
+#endif
+
 #include "src/OrthogonalSeedingTool.h"
+#include "CxxUtils/inline_hints.h"
 
 namespace ActsTrk {
 
@@ -91,6 +97,7 @@ namespace ActsTrk {
     return StatusCode::SUCCESS;
   }
 
+  ATH_FLATTEN
   StatusCode
   OrthogonalSeedingTool::createSeeds(const EventContext& /*ctx*/,
 				     const Acts::SpacePointContainer<ActsTrk::SpacePointCollector, Acts::detail::RefHolder>& spContainer,
diff --git a/Tracking/Acts/ActsPatternRecognition/src/SeedingTool.cxx b/Tracking/Acts/ActsPatternRecognition/src/SeedingTool.cxx
index 9ee205402db41d83a0ebb74ba9f158dbafa1ee27..19cdb0c48a744b348cc7862e82f0d43bb865b9a2 100644
--- a/Tracking/Acts/ActsPatternRecognition/src/SeedingTool.cxx
+++ b/Tracking/Acts/ActsPatternRecognition/src/SeedingTool.cxx
@@ -1,6 +1,11 @@
-/*  Copyright (C) 2002-2023 CERN for the benefit of the ATLAS collaboration
+/*  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
 */
 
+#if defined(FLATTEN) && defined(__GNUC__)
+// Avoid warning in dbg build
+#pragma GCC optimize "-fno-var-tracking-assignments"
+#endif
+
 #include "src/SeedingTool.h"
 
 // ACTS
@@ -11,6 +16,7 @@
 #include "Acts/Seeding/SeedFinderConfig.hpp"
 #include "Acts/Definitions/Units.hpp"
 #include "Acts/Seeding/SeedConfirmationRangeConfig.hpp"
+#include "CxxUtils/inline_hints.h"
 
 using namespace Acts::HashedStringLiteral;
 
@@ -202,6 +208,7 @@ namespace ActsTrk {
     return StatusCode::SUCCESS;
   }
 
+ATH_FLATTEN
   StatusCode
   SeedingTool::createSeeds(const EventContext& /*ctx*/,
 			   const Acts::SpacePointContainer<ActsTrk::SpacePointCollector, Acts::detail::RefHolder>& spContainer,