Intel Galileo Gen 2

Hello team Arduino! I am working on a project with intel galileo gen 2 which involves analysis of an AC circuit. I am using analogRead() to read successive voltages from a sinusoidal signal given to A0, with a 10 bit resolution. But the sampling rate I'm getting is terribly small, around 500 samples per second. I want it much higher..Could you help please? What should I do with the on-board ADC?

Chuck it out?

That's the last option. But isn't there any other way? Is the design faulty or am I missing some important step? If the ADC isn't good enough, what should I do after chucking it out? I don't know if galileo is the right choice for my project.