To be honest I don’t agree that there is a problem with the pacing, benjum. Page one sets everything up very neatly and, despite the less is more theory, the fact that there are four panels questioning the situation gives just the right amount of time for the reader to work out the twist just as it’s revealed. But I think the problem yourself and other people are seeing lies in the execution of panel four itself, because your writing gut is telling you it should be there, but it’s clear you didn’t really know what to do with it.
I suggest re-working that panel as a tight close up of Ms. Wonderment’s face and instead a more sociopathic look and the dialogue “You Hesitated”.
This will function as both a more attractive panel with clearer storytelling - that is also visually distinctive from panels 1-3 - but also give an insight into the character herself, as a someone smart enough to fool everyone into thinking she’s a superhero but unstable enough to tell someone their fatal mistake as they fall to the ground after having their neck snapped (by her).
Edit: Oh, it is also a reversal of the tight close up of Ms. Wonderment on the previous page where she is helpless which will make a very nice mirrored call back.