It can't be the history, because i see this "anomalous" usage of memory as i import the data.
Furthermore, if i apply the function ByteCount to the lists, it gives me two different results, as i wrote in the previous post, and it doesn't depend on the history...
There is also the usage of RAM during export that is different between the two cases.
If you want, i can attach an example file to explain better the problem...
