The 450 MB problem with Scribus 1.4.2

[founder]

My book, 404 pages DIN-A5, multi layer to have German and Englisch version in one document
used with Scribus 1.4.1 usual 700 MB.

Just installed 64 Bit version of Scribus 1.4.2.
Now at 1150 MB.
I checked all the setings at preferences and document setup.

There was at tools "Normal resolution preview". I had in 1.4.1 always "Low resolution preview"
I changed this both in preferences and document setup.

I closed Scribus and started new.
I checked all the setings at preferences and document setup.
Now both "Low resolution preview"

But again 1150 MB.

It's not possible to work on a 4 GB system when Scribus uses suddenly 450 MB more.