You ' ll be just fine , OP ..
Since you are flying in Suites , you will enjoy the Virgin lounge , possibly best in JFK
Was in priority line for Suites in June , before boarding .
There are various lines for TSA checks , be sure you get in the correct one . Some were in a super long one when they were " entitled " to the shorter ones just by the long one
.
Was in some short priority one here too .
There are various " stations " so if they , the TSA staff , suggest you move to another , best heed as they know where it will move faster
.
Should be ample time in Changi to browse / shop , explore the various activities - win a game or 2 perhaps , see exhibitions , taste menus from different restaurants if not in SKL ..
Even go to town , think some SIA free tour ?