Maybe, but it won't help much until you run the risk of it not starting at all. The starting capacitor is there just to make the motor begin spinning in the correct direction. It's only there until the centrifugal switch opens at about 80% speed and on a circular saw with no load, that takes place in probably less than a second. The biggest "kick" in torque is when the motor passes through what's called the "breakdown torque" part of the torque-speed curve, and that only happens AFTER the start switch has already opened. There's not really much you can do about it without creating more problems than you solve. That's one of the down sides of using single phase CSCR motors. Permanent Split capacitor (PSC) motors would have less of a jolt, but also less torque to recover from a step change in load, i.e. when the blade hits the work, and since the blades work on speed, allowing it to slow down can ruin it really fast.
There are single phase soft starters that would decrease that starting torque, but they too are risky on that type of motor, because the capacitor charging current looks like a short circuit to the SCRs, and the SCR phase angle firing that creates the reduced voltage causes harmonic heating of the capacitors. So it's usually a race to see which one fails first.
