From 2504b49239eecd6bc6ab9bdfe960ecd637b68b11 Mon Sep 17 00:00:00 2001
From: Giulio Eulisse <10544+ktf@users.noreply.github.com>
Date: Tue, 9 Jun 2026 08:57:33 +0200
Subject: [PATCH 1/2] Avoid slicing inside the inner loop

---
 PWGHF/TableProducer/trackIndexSkimCreator.cxx | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/PWGHF/TableProducer/trackIndexSkimCreator.cxx b/PWGHF/TableProducer/trackIndexSkimCreator.cxx
index f65ee16a044..61a410e10ab 100644
--- a/PWGHF/TableProducer/trackIndexSkimCreator.cxx
+++ b/PWGHF/TableProducer/trackIndexSkimCreator.cxx
@@ -3938,6 +3938,11 @@ struct HfTrackIndexSkimCreatorLfCascades {
       // cascade loop
       const auto thisCollId = collision.globalIndex();
       const auto groupedCascades = cascades.sliceBy(cascadesPerCollision, thisCollId);
+      // The bachelor track indices depend only on the collision, not on the
+      // cascade, so slice them once per collision. Each sliceBy on this Filtered
+      // join does a full arrow Table::Slice (per-column allocation) plus a
+      // selection-vector slice, so rebuilding it for every cascade is pure waste.
+      const auto groupedBachTrackIndices = trackIndices.sliceBy(trackIndicesPerCollision, thisCollId);
 
       for (const auto& casc : groupedCascades) {
 
@@ -3995,7 +4000,6 @@ struct HfTrackIndexSkimCreatorLfCascades {
         trackParCovCascOmega.setPID(o2::track::PID::OmegaMinus);
 
         //--------------combining cascade and pion tracks--------------
-        const auto groupedBachTrackIndices = trackIndices.sliceBy(trackIndicesPerCollision, thisCollId);
         for (auto trackIdCharmBachelor1 = groupedBachTrackIndices.begin(); trackIdCharmBachelor1 != groupedBachTrackIndices.end(); ++trackIdCharmBachelor1) {
 
           hfFlag = 0;

From 53ca3c7b6932fdc1ec05a7ca6ce724f9222bdc12 Mon Sep 17 00:00:00 2001
From: Giulio Eulisse <10544+ktf@users.noreply.github.com>
Date: Tue, 9 Jun 2026 15:03:39 +0200
Subject: [PATCH 2/2] Apply suggestion from @ktf

---
 PWGHF/TableProducer/trackIndexSkimCreator.cxx | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/PWGHF/TableProducer/trackIndexSkimCreator.cxx b/PWGHF/TableProducer/trackIndexSkimCreator.cxx
index 61a410e10ab..aead29025a9 100644
--- a/PWGHF/TableProducer/trackIndexSkimCreator.cxx
+++ b/PWGHF/TableProducer/trackIndexSkimCreator.cxx
@@ -3938,10 +3938,6 @@ struct HfTrackIndexSkimCreatorLfCascades {
       // cascade loop
       const auto thisCollId = collision.globalIndex();
       const auto groupedCascades = cascades.sliceBy(cascadesPerCollision, thisCollId);
-      // The bachelor track indices depend only on the collision, not on the
-      // cascade, so slice them once per collision. Each sliceBy on this Filtered
-      // join does a full arrow Table::Slice (per-column allocation) plus a
-      // selection-vector slice, so rebuilding it for every cascade is pure waste.
       const auto groupedBachTrackIndices = trackIndices.sliceBy(trackIndicesPerCollision, thisCollId);
 
       for (const auto& casc : groupedCascades) {