Don't know about a Warn, but most winches do have a "speed control" on the free spool setting.
First of all, you have to remember, that is not a gear shift lever. It is a dog clutch control.
When you put it in free, it completely disengages the spool from the gearbox and just lets the cable spool out.
Like pressing the free spool button on a casting reel.
But, since cable is prone to be springy, most of the better winches have a way to prevent backlashes.
On most worm drive winches, there is a brake pad that presses against one side of the spool to slow it down and prevent the cable from just springing out into a big backlash.
If you have one of the planetary gear winches, the brake is usually inside the spool its self.
The cable should be firm to pull off, but not very hard. When you quit pulling, it should stop immediately.
If it keeps unspooling, then the brake is either worn or needs adjusting.
Go to Warn's site, enter your model number and serial number into their replacement parts page, and it will pop up a PDF file that shows an exploded view of your winch.
Look for a brake on the parts list and refer to that number.