1. Adjust your target market. Large enterprises will always take longer than SMB's to make a purchase. However, if you build up a solid SMB market with a few Enterprises than the cycle shortens.
2. Adjust your price point and up-sell more. Large enterprises give managers and directors freedom to spend a certain amount of money each month without going through a procurement process. So one way is to adjust your basic price with enough features to get you in the door at the lower manager or director level. Then as they become dependent on your company and need more features you can get walked through the procurement much faster because it is already a vetted tool.
3. Networking is not necessarily fast on its own, but it helps drastically in cutting down the delays on sales. A good networked intro can save you 50-75% of the time you would otherwise spend getting in the door and past the gatekeepers.
4. Having a product that solves a serious pain point is critical. If you build a me to product it will take you 6-18 months to sell to large enterprises. If you build a product no one else is offering and is desperately needed by an enterprise it is crazy how fast they'll move. I had a fortune 100 firm sign a deal in less then 10 days from the first meeting when we solved a serious pain problem they were having, pricing was barely even discussed and we all kicked ourselves at that point knowing we were not priced high enough and represented too good a value.
I don't think there are "shortcuts" to take beyond working the larger businesses processes against itself.