had been optimizing

• past perfect progressive

  past perfect progressive

  Used to describe an action that was ongoing continuously in the past up until another past event interrupted it.

  of optimize.
  optimize

  verb (used with object)

  to make as effective, perfect, or useful as possible.

Related Words

• develop
• elevate
• enhance
• fine-tune
• hone
• improve
• increase
• progress
• refine
• reform
• revise
• streamline
• update
• upgrade