You don't need to copy the pixels into the streaming texture's pixel data. ...

You don't need to copy the pixels into the streaming texture's pixel data.  This behavior is defined specifically to optimize the UpdateTexture path.

Xcode-iPhoneOS/Demos/src/happy.c

@@ -164,7 +164,7 @@ main(int argc, char *argv[])
         } else if (delay > MILLESECONDS_PER_FRAME) {
             delay = MILLESECONDS_PER_FRAME;
         }
-        //SDL_Delay(delay);
+        SDL_Delay(delay);
     }
 
     /* cleanup */

src/render/opengles2/SDL_render_gles2.c

@@ -389,35 +389,13 @@ GLES2_UpdateTexture(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect
                     tdata->pixel_format,
                     tdata->pixel_type,
                     src);
+    SDL_free(blob);
+
     if (glGetError() != GL_NO_ERROR)
     {
         SDL_SetError("Failed to update texture");
         return -1;
     }
-
-    /* Update the (streaming) texture buffer, in one pass if possible */
-    if (tdata->pixel_data)
-    {
-        dest = (Uint8 *)tdata->pixel_data +
-               (tdata->pitch * rect->y) +
-               (SDL_BYTESPERPIXEL(texture->format) * rect->x);
-        if (rect->w == texture->w)
-        {
-            SDL_memcpy(dest, src, srcPitch * rect->h);
-        }
-        else
-        {
-            for (y = 0; y < rect->h; ++y)
-            {
-                SDL_memcpy(dest, src, srcPitch);
-                src += srcPitch;
-                dest += tdata->pitch;
-            }
-        }
-    }
-
-    /* Clean up and return */
-    SDL_free(blob);
     return 0;
 }