Perhaps you should try some spelling variations:
"improving a performance series." » "improving a performance metrics.", "improving a performance reviews.", "improving a performance review.", "improving _ performance series.", "improving bank performance series.", "improving loan performance series.", "improving air performance series.", "improving tax 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 food performance risks.", "improving indoor 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 a performance series.") or ("improving poor performance risks."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving a performance series.") OR ("improving poor performance risks."))*.
• Removing quotes may allow a broader search: (( improving a performance series. ) or ( improving poor performance risks. ))*.