In DC Comics, The Flash has the epithet "The fastest man alive." Who is the fastest woman alive?
Since the Flash is the fastest man alive, presumably his female counterparts are the fastest women alive in their universes. There are at least two instances of the Flash being a woman.
From this answer by Thaddeus Howze, the Flash is a woman in Superman #349 from the 1980s.
Picture from the DC Database, which credits Countdown Presents: The Search for Ray Palmer: Superwoman/Batwoman #1, February 2008
I nominate Doralla Kon of Alkomar, introduced in Flash #145, June of 1964.
In her favor: upon arrival, in her perspective, everyone near her was completely and totally frozen, with no effort on her part. Barry Allen had to teach her how to slow down, but when she did, her presence started causing explosive reactions with bodies of water. She only returns one other time hunting a fugitive from her world.
To her detriment - this is not a power. Apparently, folks from Alkomar are just like this. She's not a superheroine, she's an astronaut who just happens to come from a dimension where things move faster.
Out of universe - it is possible this particular dimension is the precursor inspiration for the Speed Force concept introduced in the 90s.
Head Canon - I like to think this chick is the culmination of a family tree of speedsters in the Speed Force who accidentally hung out in Central City in the sixties via space time weirdness.