Even thou my sybil is not the fastest Ill give you a few tips to improve on speed.
1): Smoothness and technique is important if you want to improve speed. If your sybil is rough to begin with, there is a glass ceiling of how fast you can sybil.
2): Try with maybe half the packet and see how fast you can go. Then as time progresses slowly increase the number of cards you use.
3): Do some finger exercises eg stretchin, rotating wrists etc everyday to improve dexterity.
4): The final step is practice, some people are just naturals at flourishing while others are not. eg It took me maybe 6 months to get my five face of sybil to look fairly decent, while my friends got it down smooth within 2 weeks.