Perhaps you should try some spelling variations:
"improving food performance series." » "improving food performance metrics.", "improving food performance reviews.", "improving food performance review.", "improving good performance series.", "improving fund performance series.", "improving bond performance series.", "improving land performance series."
"improving poor performance risks." » "improving poor performance risk.", "improving poor performance issues.", "improving poor performance based.", "improving export performance risks.", "improving sector performance risks.", "improving _ performance risks.", "improving power performance risks.", "improving indoor performance risks.", "improving labor performance risks."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving food performance series.") or ("improving poor performance risks."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving food performance series.") OR ("improving poor performance risks."))*.
• Removing quotes may allow a broader search: (( improving food performance series. ) or ( improving poor performance risks. ))*.