Tor Lillqvist (and others) have done a lot to add the Calc feature of Threaded Calculation (i.e., multi-threading / parallelism). It is now enabled by default in version 6.0+.
Since this is a new feature, we expect that a lot of bugs may appear which may be related to this. This is a meta tracker for Calc Threaded Calculation bugs.
More about multi-threading in Calc:
LibreOffice Calc Is Finally Being Threaded
Making Calc Calculate in Parallel
Bug 114157 may be the first bug I have fould to be related to Calc multi-thread calculation.