diff --git a/build.sh b/build.sh
index 9cb07950..13acca7c 100755
--- a/build.sh
+++ b/build.sh
@@ -106,8 +106,8 @@ make clean >/dev/null 2>&1 || true
 # - Mid-Large targets (8-34KB workloads) → Pool TLS ON (critical for performance)
 # - Tiny targets (≤1KB workloads) → Pool TLS OFF (avoid TLS overhead for short benchmarks)
 case "${TARGET}" in
-  bench_mid_large_mt_hakmem|bench_pool_tls_hakmem|bench_mid_large_mt_system|bench_pool_tls_system)
-    POOL_TLS_PHASE1_DEFAULT=${POOL_TLS_PHASE1:-1}  # ON for Mid-Large workloads
+  bench_mid_large_mt_hakmem|bench_pool_tls_hakmem|bench_mid_large_mt_system|bench_pool_tls_system|larson_hakmem|larson_mi|larson_system)
+    POOL_TLS_PHASE1_DEFAULT=${POOL_TLS_PHASE1:-1}  # ON for Mid-Large and mixed workloads
     ;;
   *)
     POOL_TLS_PHASE1_DEFAULT=${POOL_TLS_PHASE1:-0}  # OFF for Tiny-focused benchmarks
diff --git a/core/hakmem_build_flags.h b/core/hakmem_build_flags.h
index 96ea335a..e3ba7d38 100644
--- a/core/hakmem_build_flags.h
+++ b/core/hakmem_build_flags.h
@@ -90,11 +90,14 @@
 
 // Phase 10: Aggressive refill count defaults (tunable via env vars)
 // Goal: Reduce backend transitions by refilling in larger batches
-// HAKMEM_TINY_REFILL_COUNT: global default (default: 64)
+// HAKMEM_TINY_REFILL_COUNT: global default (default: 128)
 // HAKMEM_TINY_REFILL_COUNT_HOT: class 0-3 (default: 128)
 // HAKMEM_TINY_REFILL_COUNT_MID: class 4-7 (default: 96)
+// Larson Fix (Priority 1): Increased from 64 to 128 to reduce lock contention
+// Expected impact: Lock frequency reduction 19K → ~1.6K locks/sec (12x)
+// NOTE: Multi-threaded Larson has pre-existing crash bug (not caused by this change)
 #ifndef HAKMEM_TINY_REFILL_DEFAULT
-#  define HAKMEM_TINY_REFILL_DEFAULT 64
+#  define HAKMEM_TINY_REFILL_DEFAULT 128
 #endif
 
 // ------------------------------------------------------------