Prompt; quick or speedy — indicating that something is done without delay. A quasi-adjectival expression usable in both written and spoken language.
速やかに問題を報告してください。
Please report the problem promptly.
速やかな対応のおかげで被害を最小限に抑えられた。
Thanks to the prompt response, the damage was kept to a minimum.
手続きは速やかに進められた。
The procedures were carried out swiftly.