|Which has less mass, steel or air? On most planets, an air bladder is much lighter than a steel spring. There are other performance parameters, but air springs are light. A suspended air fork for a bicycle can often be almost the same weight as a dead rigid steel fork.
Another great advantage of the air suspension system is easy adjustability. Varying the air pressure in the positive, or positive and negative chambers can tune a proper ride.
Currently, suspension forks are designed for off-road, intending to resist big impacts. If I were to design a new fork for street riding, it would be rather different. But for today, using currently available forks, a rider can tune the pressures in the chambers to increase performance for the street.
We already know that speed on rough urban pavement can be increased with the use of suspension forks; as seen in the diagram on this page.
Performance in speed and handling, especially cornering can be improved by mis-tuning the forks contrary to the off-road recommendations. The tuning objective is to reduce the resistance to being pushed in, and to get the forks to push out quickly, like my Yamaha FZR. Street riding impacts are small; variations in pavement level more often go down. I want my fork to absorb the small bumps, and I want that wheel pushed out onto the ground when the road drops away from me. Like I say, this is really beneficial while cornering.
For dual chambered air forks, such as the Rock Shox SIDs I like to use, the fundamental is to make the negative chamber slightly higher pressure than the positive. Around 5 to 8 percent higher. An additional advantage is this allows the bicycle to ride lower, also improving handling. The baseline pressure, whether 100 psi or 140 psi will be determined by rider weight and preference (I prefer around 100). Then to improve street performance, and if you like to ride at 100 psi, put that negative chamber at 105 psi. Or if you like it rougher, go 140 pos / 151 neg.
Go faster than cars.