diff --git a/src/mesa/state_tracker/st_cb_bufferobjects.c b/src/mesa/state_tracker/st_cb_bufferobjects.c
index 55f3644..d68e1e9 100644
--- a/src/mesa/state_tracker/st_cb_bufferobjects.c
+++ b/src/mesa/state_tracker/st_cb_bufferobjects.c
@@ -256,8 +256,15 @@ st_bufferobj_data(struct gl_context *ctx,
          break;
       case GL_STREAM_DRAW:
       case GL_STREAM_COPY:
-         pipe_usage = PIPE_USAGE_STREAM;
-         break;
+         /* XXX: Remove this test when we have PBO unpack acceleration. Right
+          * now, PBO unpacking is done by the CPU, so we have to make sure
+          * CPU reads are fast.
+          */
+         if (target != GL_PIXEL_UNPACK_BUFFER_ARB) {
+            pipe_usage = PIPE_USAGE_STREAM;
+            break;
+         }
+         /* fall through */
       case GL_STATIC_READ:
       case GL_DYNAMIC_READ:
       case GL_STREAM_READ: