MuseScore takes very long on opening some 2.X scores
1) Open a score from https://musescore.com/openscore/scores/4861738 (can't attach it here since it exceeds the limit of 4MB)
Result: MuseScore hangs.
According to debugger it hangs somewhere around this line, possibly in the surrounding loop.
Tested on current master, 3.4.2 version opens this file just fine.
OS: Debian GNU/Linux 10 (buster), Arch.: x86_64, MuseScore version (64-bit): 3.5.0, revision: a5c92e2