Pandoc allows to access and modify the Haskell runtime system (RTS) that the program runs on.
E.g., to print memory usage:
pandoc +RTS -s -RTS …
Or to limit the maximum heap size available to pandoc to 2 GB:
pandoc +RTS -M2G -RTS …
See all available options by running:
pandoc +RTS -?
This can be helpful when facing performance issues.