Neon lamps are low frequency devices on due to the time it takes to ionize and de-ionize the gas (see pearson-anson effect). However slow is relative and some lamps can be run at frequencies as high at 20kHz. The higher the frequency, the less the bulb will appear to flicker. I would check the manufacturer rating and see what they recommend however, as increasing the frequency will increase the voltage and current demands which may impact the lifespan of the bulb or other parts of your circuit as it will generate more heat.

So yes a neon bulb could run at 300Hz, likely reducing the bulbs lifespan, but check the manufacturer ratings first.