Yep. And nothing is gained by speaking so quickly. It's one thing doing so in a shop or a bar in New York city, but at a large, complex, busy airfield; where safety is critical, and many foreign crews operate; speaking slowly and clearly is very much a good idea.
You want everyone to clearly hear and understand, (and write down) clearances. There is no need to speak so fast, (and risk misunderstandings or having to repeat). It sometimes seems to me to be the oral equivalent of driving with one hand on the wheel and one arm leaning on the window ledge - it might look flash but it is less safe.
