I've always found the older Tom Toms really slow to get a GPS fix, especially if moving or in a poorer signal area. GPS quick fix is software cheat which tells the device where the satellites are - speeding up the process. Presumably the Garmin models might be quicker at acquisition.

To speed the process up on the Tom Tom - go to the GPS screen showing the satellites and signals being received - and position / hold the unit so that at least three grey bars are continuously above the horizontal line - three seconds after the next half minute mark you should get a lock and the bars will change to solid blue.