Hasta La Motion!

i´m not sure about a little thing i tested:
i loaded a read(sourceX.%04d.jpg) an duplicated it 20 times. so every read kept the same source file. i did some modifikations like transform, blur ASO (nothing specific) and merged one after the next. when watching the last node while playback, it was fast , but let´s say took 1 sec per frame.

i copied the complete setup. only difference was, that i just connected 1 read node to all the inputs.
this setup ran 3 times faster!??

i thought nuke was smart enough to recognize that 20 read nodes with exactly same settings and same path act like one of them!!
am i wrong with that, or what´s it all about?

and what does it mean when dealing with multipass EXR? better load only one exr-read in script and branch this one to all the pass-merge operations?

thanks in advance!!