Perf board parasitic capacitance fries microcontroller?
I also doubt parasitic capacitance is the issue here. I simulated a circuit with 100pF to ground (a huge amount) and a faux mosfet gate termination. and only saw ~5mA though it with rise/fall times of 100ns. If your rise times are much faster you will see more current, but according to this post: 

How solder inductance affects RF circuits?

you'd be lucky to get significantly more than 1-5pF on the line. 



Huge cap on input for testing's sake.





Current through cap





Do you have schematics/pictures of the circuit? is it possible that you shorted two wires and that's why you draw so much current?