Perhaps you should try some spelling variations:
"improving do performance metrics." » "improving do performance measures.", "improving di performance metrics.", "improving 2 performance metrics.", "improving 3 performance metrics.", "improving co performance metrics.", "improving eco performance metrics.", "improving pro performance metrics."
"improving bar performance series." » "improving bar performance studies.", "improving bar performance size.", "improving zur performance series.", "improving der performance series.", "improving fur performance series.", "improving care performance series.", "improving burn performance series.", "improving air performance series."

Try widening your search to All Fields.

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

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