Kohei Yoshida at Collabora is working on improving the spread-sheet component of LibreOffice, Calc, with some multi-threaded support. Kohei is working on allowing formula cell compilations to occur in multiple threads during XLSX file importing. When opening the Microsoft Excel OpenXML Spreadsheets, the goal is to utilize one CPU thread per sheet.
The initial support for multi-threaded XLSX importing was committed to Git yesterday, but it's still stuck being single-threaded until Calc core and other code has been made more multi-threaded friendly in dealing with reentrancy.
Let's hope more of LibreOffice will become OpenCL and multi-threading friendly in due time.