Hello~ Actually, in my understanding, the SpaceToDepth op can be totally achieved by reshape and transpose Ops
Below is a quick test:

I've updated the yolov5s optimization python script here

To keep the slice op as it is, one can simply try:
$ python3 yolov5s-opt.v2.py --input yolov5s.v5.onnx --output yolov5s.v5.opt.onnx --out_tensor 397,458,519
To replace the slice op by reshape and transpose op, one can try:
$ python3 yolov5s-opt.v2.py --input yolov5s.v5.onnx --output yolov5s.v5.opt.onnx --in_tensor 167 --out_tensor 397,458,519

A quick glance at the converted tmfile models:

The output results are exactly same during my test ~

However, with my ubuntu PC, I didn't see too much difference of the performance between these tmfiles.
Maybe you can have a try with some other devices (I'm always lack of hardware resources ...) and share me your test results~

@stevenwudi @BUG1989