--- old/src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.cpp	2018-06-18 18:34:29.900479017 +0200
+++ new/src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.cpp	2018-06-18 18:34:29.724481012 +0200
@@ -27,6 +27,7 @@
 #include "gc/shenandoah/shenandoahConnectionMatrix.hpp"
 #include "gc/shenandoah/shenandoahHeap.hpp"
 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
+#include "gc/shenandoah/shenandoahHeuristics.hpp"
 #include "gc/shenandoah/shenandoahRuntime.hpp"
 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
 #include "interpreter/interpreter.hpp"
@@ -48,6 +49,11 @@
 void ShenandoahBarrierSetAssembler::arraycopy_prologue(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
                                                        Register src, Register dst, Register count) {
 
+  if (ShenandoahHeap::heap()->heuristics()->can_do_traversal_gc()) {
+    // Don't need arraycopy-pre-barrier for traversal. No need to pointlessly
+    // call out to runtime.
+    return;
+  }
   bool checkcast = (decorators & ARRAYCOPY_CHECKCAST) != 0;
   bool disjoint = (decorators & ARRAYCOPY_DISJOINT) != 0;
   bool obj_int = type == T_OBJECT LP64_ONLY(&& UseCompressedOops);