Full speed is an expression used when referring to something that is moving quickly or happening at a fast pace. However, there are several alternatives to this phrase that can be used depending on the context or personal preference. For instance, the phrase "top speed" is a popular substitute that is frequently used to indicate something that is moving at its highest possible velocity. Another synonym is the term "breakneck speed," which is often used when referring to a dangerous or reckless speed. Other options include the phrases "maximum velocity," "blazing speed," and "lightning-fast." All of these alternatives serve as effective alternatives to the phrase "full speed," and can add a touch of variety to one's language.