... is surprisingly expensive
shaves about 5% off the time to build this chart

Change-Id: I8e5d071edba50d264c2ab01c6bc0b2cad0e41ec6
Reviewed-on: https://gerrit.libreoffice.org/20588Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>