Rainer,

> Investigating this symptom I found that with the non-GUI processes I
> always follow the procedure:
>
> * Set query SQL
> * Open query
> * Read/write desired data
> * Close query
> * Commit
>
> With the GUI application I can't do this. Here I am using Query.refresh
> to update the visualization.

Query.refresh retrieves the whole dataset from the server again.
If you have a big dataset and/or you do the above steps in a loop,
it is no wonder that the CPU is stressed ....

Harald