A Speed Bonus Chain is like a combo. It keeps getting bigger until you fail to connect a pairs within two seconds. You need a Speed bonus of 30 for "Nimble" achievement and 150 for "Supersonic." A Speed Chain of 30 isn't very hard to obtain with a little bit of experience in the game.
A Speed Chain of 150 is a lot harder. The best mode for trying this is the Color Charge in the Daily Challenge. A two or three-star rated puzzle should have enough blocks to pull this off. The Speed Chain will carry over from one puzzle to the next so long as you do not delay in making a match when the new puzzle starts. Personally, I've made Speed Chains well in excess of 200, so just keep practicing and waiting for a good puzzle sequence and you'll eventually unlock this.