Perhaps you should try some spelling variations:
"improving _ performance metrics." » "improving _ performance contracts.", "improving _ performance measures.", "improving _ performance contract."
"improving tax performance series." » "improving tax performance reviews.", "improving tax performance review.", "improving tax performance targets.", "improving a performance series.", "improving can performance series.", "improving dam performance series.", "improving trade performance series.", "improving land performance series.", "improving data performance series."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving tax performance series.") or ("improving _ performance metrics."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving tax performance series.") OR ("improving _ performance metrics.")).
• Removing quotes may allow a broader search: (( improving tax performance series. ) or ( improving _ performance metrics. )).
• Adding a wildcard symbol may retrieve word variants: (("improving tax performance series.") or ("improving _ performance metrics."))*.