New pdf viewer not stable in floating window with large files

Win 10 Desktop app
This problem occurs with large (800+) pages pdf files.
When opening a pdf file then clicking “move to new window”, the pages doesn’t always render. Sometimes they appear normally and sometimes few pages are displayed than blanck… no pages displayed… Restarting the app solves it, but then it appears again after working for a few minutes.
P.S. Is it possible to have an option to revert to the old PDF viewer?
thanks in advance!

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