There are several ways to adjust the spped of timeline events.
If you want the speed to be constant for the entire event, then just Ctrl/Drag the edge.
If you need variations in speed, add a velocity envelope by right-clicking>Insert Envelope>Velocity. Double-click on the line that appears and you can make points that can be dragged around to create the speed changes.
Gary Kleiner
Learn Vegas and DVD Architect
http://www.VegasTrainingAndTools.com