diff --git a/renderdoc/driver/d3d12/d3d12_commands.cpp b/renderdoc/driver/d3d12/d3d12_commands.cpp
index 50b780890..76b7b4b69 100644
--- a/renderdoc/driver/d3d12/d3d12_commands.cpp
+++ b/renderdoc/driver/d3d12/d3d12_commands.cpp
@@ -162,7 +162,10 @@ WrappedID3D12CommandQueue::WrappedID3D12CommandQueue(ID3D12CommandQueue *real,
   }
   else
   {
-    m_pSerialiser = new Serialiser(NULL, Serialiser::WRITING, debugSerialiser);
+    // make serialisers smaller by default since we create a lot of these internally for small
+    // commands.
+    // User lists will quickly grow to a steady-state over time.
+    m_pSerialiser = new Serialiser(NULL, Serialiser::WRITING, debugSerialiser, 256);
 
     m_pSerialiser->SetDebugText(debugSerialiser);
   }
diff --git a/renderdoc/serialise/serialiser.cpp b/renderdoc/serialise/serialiser.cpp
index 02c46fdab..132644716 100644
--- a/renderdoc/serialise/serialiser.cpp
+++ b/renderdoc/serialise/serialiser.cpp
@@ -634,7 +634,7 @@ Serialiser::Serialiser(size_t length, const byte *memoryBuf, bool fileheader)
   }
 }
 
-Serialiser::Serialiser(const char *path, Mode mode, bool debugMode)
+Serialiser::Serialiser(const char *path, Mode mode, bool debugMode, uint64_t sizeHint)
     : m_pCallstack(NULL), m_pResolver(NULL), m_Buffer(NULL)
 {
   m_ResolverThread = 0;
@@ -935,7 +935,7 @@ Serialiser::Serialiser(const char *path, Mode mode, bool debugMode)
     }
     else
     {
-      m_BufferSize = 128 * 1024;
+      m_BufferSize = sizeHint;
       m_BufferHead = m_Buffer = AllocAlignedBuffer((size_t)m_BufferSize);
     }
   }
diff --git a/renderdoc/serialise/serialiser.h b/renderdoc/serialise/serialiser.h
index 304ca32b0..cbfa78b1a 100644
--- a/renderdoc/serialise/serialiser.h
+++ b/renderdoc/serialise/serialiser.h
@@ -199,7 +199,7 @@ public:
   // Init and error handling
 
   Serialiser(size_t length, const byte *memoryBuf, bool fileheader);
-  Serialiser(const char *path, Mode mode, bool debugMode = false);
+  Serialiser(const char *path, Mode mode, bool debugMode, uint64_t sizeHint = 128 * 1024);
   ~Serialiser();
 
   bool HasError() { return m_HasError; }