Hi,
The edit and transform lop always add transform attribute to prim.

I dont want the matrix stack and only need a fresh and clean stage.

How to flatten these transforms into one local matrix?

Does chained matirx affect the final performance?

LOPs does not currently provide a tool to manipulate transforms in this way, though it is something that is on our radar for future work.

Certainly having more transforms has _some_ effect on the performance of the scene, but unless you're adding many, many transforms to many, many prims, I wouldn't expect it to be noticeable. Obviously everything depends on the size of your scene though, and how important an extra 1% of performance is (sometimes every bit matters). But there are lots of performance targets I'd go after in a USD scene before worrying about the number of transforms.

That said, if you do want to tackle this, you can always use Wrangle LOPs to "transform" the transform stack on a prim.