Feel free to email me or to post your block of script for me to take a look.

Thanks.

To delete them, first open their worksheet. To do this, type 'edit DatasetName'. You can then close the worksheet, deleting the datasets.

If this doesn't help, then I will have to think further.

Well, it took so long even when I type that line alone... I isolated the problem on that line, I'm sure. I have more or less solved my problem with a curious method: I imagined that it had to do somehow with my project (as in other new projects it worked fast), so I re-made the project by saving every window, one by one, worksheets and graphs, and loading them again in a new fresh project, by this conserving my data but avoiding any other strange stuff that could be there after many hours of work over the old project. With this the problem disappeared, and that command run fastly again (and consequently all my scripts where I use it).

This is not the first time that I have to avoid a weird problem by using this method. It is slow, but sometimes is a good solution for the strange, unpredictable behavior of computers and software :-)

Great, happy to hear that you found a solution.

When you resaved your Origin windows to create the new project, did the windows keep their original names. In other words, I wonder it it had to do with the window names that you were using.

What strings were %H and %U set to?

What I did is not exactly a solution, because after some days of work with the repaired project it becomes slower again. It would be nice to know the reason, to avoid it or to directly attack it :-) Could be something related with increasing amount of temporary hidden datasets that occupy more and more memory? I don't know...

But this can give a clue: what really goes slowly is the renaming process itself, not only the command. It happens the same when I rename the windows with Windows/Rename, or if I move the window to a sub-folder...

jose.