The phrase "quickened speed" is commonly used to describe an increase in pace or momentum. However, there are a variety of synonyms that can be used to convey a similar meaning. These include terms such as accelerated, hastened, expedited, hurried, and rushed. Each of these words suggests a sense of urgency or heightened energy, and can be applied in a variety of contexts. Whether referring to physical movement, mental processing, or emotional intensity, these synonyms provide a range of options for expressing the idea of increased speed or intensity. Ultimately, the choice of which word to use will depend on the specific context and intended tone of the message being conveyed.