阿山 15 年來一直擔任 FixMyCar.com 的行銷人和網站管理員。為了讓使用者對網站更加滿意，他和開發人員團隊已投入許多心力。不過，效能指標最近卻顯示網站速度有隨著時間大幅減慢的現象。 哪一項長期維護計畫可限制會影響效能的特定指標，因而派上用場？

A performance budget is a set of defined limits on performance metrics (like page load time, image size, or script execution time) that a website or application should not exceed. It acts as a proactive, long-term maintenance plan by establishing thresholds that developers must adhere to during development and updates. This prevents performance degradation over time, as new features or content are continuously checked against these budgets. "Performance maintenance team" is a group of people, not a plan. "Independent testing plan" focuses on testing methodologies, not necessarily on setting and enforcing specific performance limits. "Long-term performance audit" is a reactive measure to assess performance periodically, rather than a proactive budget to prevent issues.