When something requires speedy action, it means that immediate action needs to be taken to avoid consequences or solve a problem. Some synonyms for this term include urgent, pressing, impelling, critical, imminent, and exigent. These words signify a level of urgency that demands quick thinking and rapid response. Other synonyms that convey a sense of urgency and speed include crucial, essential, necessary, timely, important, and vital. All of these words suggest a situation that requires quick action to prevent further harm or resolve an issue before it worsens. In summary, any term that implies urgency or haste would be a suitable synonym for the phrase "requiring speedy action".