Trail Designs's Vari-Vent Windscreens are a good value piece of kit that will increase your stoves efficiency and speed of boiling. Use one of these windscreens, available in 3 sizes, around any type of stove and you should see improved performance in even the slightest of winds. Features strategically placed air flow holes that let enough air to the stove to allow efficient combustion.
Trail Designs says:
Introducing an important innovation in windscreen design, the Vari-Vent! Traditional/Classic/MSR-style windscreens require air to come over the top of your screen and by your pot to fuel your stove. Windscreens with perforation along the bottom don't block the wind and require you to do unnatural acts with boulders.
The patent pending Vari-Vent technology provides a series of variable vents along the bottom edge of your windscreen, allowing you to close off the upwind side while keeping the downwind side open. Further, by allowing you to customize your windscreen venting in the field, and offering a range of heights (nominally 4", 6" and 8" - 28" long) to fit your system, you can get it closer to, and higher up, your pot.
The edges are rolled to make it stronger and safer to use. The screen will fold flat for storage or you can wrap it around your fuel bottle. (4" and 6" screens run 3/8" taller than nominal).