I know this doesn’t apply to every single person who plays the instrument, but I have found faster passages to be much easier when the finger engages with the key and releases quickly to allow for a little bit of space between each of the notes in the groupings. I am certainly not saying that everything is to be played staccato, but the quicker the finger activates and releases the key, the faster and cleaner your scale/arpeggio passages will become at your desired tempo.
I know I’ve mentioned this in many other posts here, but I’ll say again that the faster your fingers move through a passage of scales or arpeggios, the lighter and less “in the key” you must play through the note groupings. You have to be very careful when slow practicing any passage that requires speed and agility. My rationale for saying this is because when you move slower on the keyboard, the tendency is to remain in the key for a longer period of time due to the fact that the technical requirements at a slower tempo are much easier than when a performance tempo is faster. Here is what I suspect is happening: