When the word "busier" isn't cutting it, there are plenty of other synonyms to use instead. For instance, one could use "more active," indicating a higher level of physical or mental activity. "More occupied" could also work, meaning someone is more preoccupied with various tasks. "More engaged" can be a more professional term that denotes being absorbed in work or a project. Additionally, one could use "more hectic" to convey a more frenzied atmosphere or "more bustling" to suggest a crowded or busy environment. Ultimately, there is no shortage of alternative words to convey a more dynamic or active state, depending on the context in which one wishes to use them.