diff --git a/CMakeLists.txt b/CMakeLists.txt
index efb2e31..e9737aa 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,6 +16,9 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 # flto required as xxhash is also built with flto to allow efficient inlining
 # of the hash functions.
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -gdwarf-4 -stdlib=libc++ -flto")
+# For benchmarks: easier profiling & links against system installed googlebench
+# if that was build with non libcxx.
+# set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -gdwarf-4 -flto -fno-omit-frame-pointer")
 set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -g -O0 -fsanitize=address")
 set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} -g -O3")
 set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O3")
diff --git a/src/algebra/Join.cpp b/src/algebra/Join.cpp
index 6b11b75..1397716 100644
--- a/src/algebra/Join.cpp
+++ b/src/algebra/Join.cpp
@@ -330,5 +330,4 @@ void Join::decayPkJoin(inkfuse::PipelineDAG& dag) const {
       // End vectorized Block.
    }
 }
-
 }
diff --git a/src/exec/FuseChunk.h b/src/exec/FuseChunk.h
index 6cc394a..f6dcef7 100644
--- a/src/exec/FuseChunk.h
+++ b/src/exec/FuseChunk.h
@@ -9,8 +9,8 @@
 
 namespace inkfuse {
 
-/// Default chunk size (4096)
-const uint64_t DEFAULT_CHUNK_SIZE = 4096;
+/// Default chunk size 512
+const uint64_t DEFAULT_CHUNK_SIZE = 512;
 
 /// A column within a FuseChunk.
 struct Column {
diff --git a/src/exec/runners/InterpretedRunner.cpp b/src/exec/runners/InterpretedRunner.cpp
index 19660ac..839b720 100644
--- a/src/exec/runners/InterpretedRunner.cpp
+++ b/src/exec/runners/InterpretedRunner.cpp
@@ -1,5 +1,4 @@
 #include "InterpretedRunner.h"
-#include "algebra/suboperators/row_layout/KeyPackerSubop.h"
 #include "algebra/suboperators/sources/TableScanSource.h"
 #include "interpreter/FragmentCache.h"
 
@@ -27,6 +26,14 @@ InterpretedRunner::InterpretedRunner(const Pipeline& backing_pipeline, size_t id
          .fuse_chunk_ptrs{original_context.getNumThreads()},
       };
    }
+
+   // Extract all key packer IUs as these need special treatment during interpretation.
+   for (const auto& subop : pipe->getSubops()) {
+      if (auto* as_key_packer = dynamic_cast<KeyPackerSubop*>(subop.get())) {
+         assert(as_key_packer->getSourceIUs().size() == 2);
+         key_packer_ius.push_back(as_key_packer->getSourceIUs()[1]);
+      }
+   }
 }
 
 InterpretedRunner::~InterpretedRunner() {
@@ -58,12 +65,8 @@ Suboperator::PickMorselResult InterpretedRunner::pickMorsel(size_t thread_id) {
       // It could be that we require scratch pad IUs within this pipeline.
       // As these are never officially produced by an expression, we need
       // to make sure their sizes are set up properly.
-      for (const auto& subop : pipe->getSubops()) {
-         if (dynamic_cast<KeyPackerSubop*>(subop.get())) {
-            assert(subop->getSourceIUs().size() == 2);
-            const IU* scratch_pad_iu = subop->getSourceIUs()[1];
-            context.getColumn(*scratch_pad_iu, thread_id).size = picked->morsel_size;
-         }
+      for (const IU* key_packer_iu : key_packer_ius) {
+         context.getColumn(*key_packer_iu, thread_id).size = picked->morsel_size;
       }
    }
 
@@ -99,10 +102,8 @@ void InterpretedRunner::runZeroCopyScan(size_t thread_id) {
       zero_copy_state->fuse_chunk_ptrs[thread_id] = context.getColumn(*zero_copy_state->output_iu, thread_id).raw_data;
    }
    // Get the state of the picked morsel.
-   TScanDriver* driver = dynamic_cast<TScanDriver*>(pipe->suboperators[0].get());
-   TScanIUProvider* provider = dynamic_cast<TScanIUProvider*>(pipe->suboperators[1].get());
-   assert(driver);
-   assert(provider);
+   TScanDriver* driver = reinterpret_cast<TScanDriver*>(pipe->suboperators[0].get());
+   TScanIUProvider* provider = reinterpret_cast<TScanIUProvider*>(pipe->suboperators[1].get());
    const auto driver_state = reinterpret_cast<LoopDriverState*>(driver->accessState(thread_id));
    const auto provider_state = reinterpret_cast<IndexedIUProviderState*>(provider->accessState(thread_id));
    // And directly update the target fuse chunk column.
diff --git a/src/exec/runners/InterpretedRunner.h b/src/exec/runners/InterpretedRunner.h
index eeed2db..1b29904 100644
--- a/src/exec/runners/InterpretedRunner.h
+++ b/src/exec/runners/InterpretedRunner.h
@@ -2,6 +2,7 @@
 #define INKFUSE_PIPELINEINTERPRETER_H
 
 #include "PipelineRunner.h"
+#include "algebra/suboperators/row_layout/KeyPackerSubop.h"
 #include <functional>
 #include <map>
 #include <string>
@@ -52,6 +53,8 @@ struct InterpretedRunner final : public PipelineRunner {
       std::vector<char*> fuse_chunk_ptrs;
    };
    std::optional<ZeroCopyScanState> zero_copy_state;
+   /// Key packing suboperators IUs in the interpreted graph.
+   std::vector<const IU*> key_packer_ius;
    /// Custom interpreter for a zero copy scan.
    void runZeroCopyScan(size_t thread_id);
 };