Depends where you live in Jersey City. Exchange Place to WTC is 1 stop and takes 4 mins on a weekday - http://www.panynj.gov/path/full-schedules.html

Hoboken to Christopher St takes about 8 mins.

Alternatively, you can also take ferries.

Driving through any of the tunnels is pretty painful on bad days.

It must have gotten worse since I left the US. Even from Journal Square it never took me more than 20 minutes to WTC, though train frequency did slow down late at night.