Practice and knowledge of logic
I am averaging about 400 seconds at the moment, but my best is 120 seconds for a 4x4 and 280 for a 4x5
Working out the ones with really low solve percentages has been a big help, as is starting fresh.
Also it takes about a minute to read the questions, so you only have about 30 or so seconds to make 30 clicks plus any red Xes you need to make.
So doable to get a record but you it takes a bit of luck to pick the correct starting point.
practice is really important, just like learning your multiplication tables.