When T2 Fast Track (Gold Track) was introduced it was usually a little bit quicker than standard. On most occasions now it's little more than a vanity product (and yes, I'm still vain enough to use it as a *G so guilty as charged).

Unlike, say, the BA First Wing in T5 the scanning machines have not been updated so currently you're taking everything out of your bag and repacking it. The queues often snake through the tensabarriers. It really is anything but a premium experience.

If you've got it by default with the train ticket then you might as well use it (although note if you have a very early flight it won't be open anyway, and nor does it operate to a guaranteed opening time) but don't expect any better experience than through the standard security and possibly worst.