Perhaps you should try some spelling variations:
"improving co performance contract." » "improving co performance contracts.", "improving ceo performance contract.", "improving do performance contract.", "improving core performance contract.", "improving eco performance contract.", "improving crop performance contract.", "improving ict performance contract."
"improving upper performance reviews." » "improving upper performance review.", "improving upper performance reports.", "improving upper performance risks.", "improving under performance reviews.", "improving support performance reviews.", "improving capped performance reviews.", "improving supply performance reviews.", "improving budget performance reviews.", "improving gender performance reviews."

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

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