WARNING: The following contains spoilers for WandaVision Episode 6, "All-New Halloween Spooktacular!" now streaming on Disney+.
The Marvel Comics character Quicksilver has three live-action versions of himself, being played by Evan Peters in Fox's X-Men franchise, and having two iterations of the character in the Marvel Cinematic Universe, with Aaron Taylor-Johnson playing him in Avengers: Age of Ultron and Peters returning for a new version of the character in WandaVision. While these are all iterations of the same character, they have their differences, with Fox's Quicksilver being the fastest of the three.
X-Men's Quicksilver Is Faster Than a Bullet
Quicksilver's big screen debut was in X-Men: Days of Future Past, and his super speed was more than helpful, with Beast, Professor X and Wolverine recruiting him to help break Magneto out of the Pentagon. Upon initially meeting the speedster, who goes by Peter in this franchise, Beast confuses his super speed with teleportation because Quicksilver moves so fast he's practically invisible.
Agreeing to the prison break, Peter shows just how quick he is when the guards fire their guns at him, Magneto, Professor X and Wolverine. He moves faster than a bullet, incapacitating several guards and moving several bullets out of the way so they miss his mutant allies. This scene alone proves he is faster than the original MCU Pietro.
Age of Ultron's Pietro Couldn't Outrun Death
In Age of Ultron, a plane shoots an automatic weapon at Clint Barton, who shields a kid; however, Pietro arrives just in time to push a car in front of the Avenger, but he is shot several times himself. The X-Men's Quicksilver was not only able to avoid gunfire, but he was also able to save three people while keeping himself safe and incapacitating their enemies. Age of Ultron's Quicksilver, on the other hand, was unable to avoid gunfire while saving others.
It should be taken into account that Peter was only dealing with a handful of bullets, not a barrage of bullets. Plus, this was a spur of the moment decision, so Pietro may not have been thinking through every option. However, in X-Men: Apocalypse, Peter faces a much larger threat, with the Xavier School for Gifted Youngsters exploding. With little time to think, Peter rushes into the school, devises a plan to save every student and successfully rescues everyone aside from Havok. He was fast enough to do all this without getting injured, but Pietro couldn't save two people with sacrificing himself.
WandaVision's Pietro Remains a Mystery
As for the new Pietro, he claims to be the Quicksilver from Age of Ultron, even though he looks and sounds different. If he truly is this Pietro, despite the changes, then he would still be slower than X-Men's Quicksilver.
However, if this Pietro isn't the one from Age of Ultron, then it's harder to test his speed against the other iterations of the character since he uses his powers for minor things, like goofing off with his nephews. Despite this, audiences see him use his powers when he pranks the neighborhood, and it appears Wanda can somewhat track her brother's actions too. The fact that this Pietro is more visible when he moves could mean he is slower than Fox's Quicksilver, who was much harder to see.
The show could be making him more visible so audiences can better see what he is doing, similar to how the X-Men films slowed everything down to show what Quicksilver was doing while using his super speed. However, in WandaVision, time does not slow down around Pietro, instead showing a blue blur moving around, with a few moments featuring Pietro himself, like when he's smashing the pumpkins.
This is similar to how the X-Men films would also show a quick blur to indicate that Peter used his mutant abilities. While both use a similar technique to show the audience that he's using his super speed, when it happens in the X-Men films, Quicksilver's body cannot be seen until he stops using his powers, hence why Beast thinks he's a teleporter. Meanwhile, audiences see WandaVision's Pietro clearly every so often when in action, and Wanda, unlike Beast, can somewhat follow her brother's movements; although, she's struggling.
Because of this, it stands to reason that this Pietro is also slower than Fox's Quicksilver. However, it's hard to tell since his powers have not been applied to a life or death situation. Plus, with his mysterious origin, there's always the possibility he's holding back or hiding something, like the full capabilities of his powers. Until more is revealed, X-Men's Peter remains the fastest Quicksilver at the time of this writing.
Written by Jac Schaeffer and directed by Matt Shakman, WandaVision stars Elizabeth Olsen as Wanda Maximoff/Scarlet Witch, Paul Bettany as Vision, Randall Park as Agent Jimmy Woo, Kat Dennings as Darcy Lewis, Teyonah Parris as Monica Rambeau and Kathryn Hahn as Agnes. New episodes air Fridays on Disney+.