Our current understanding of electrons is governed by quantum mechanics, so the only physics based answers that I can see giving are based on quantum mechanics.
If we stop time for the electrons, they will appear to hold still. Now if we do this by introducing a discontinuity in the laws of physics, where most of the world is governed by real physics, and the electrons are being governed by some new laws completely unrelated to real physics, then the answer can be anything we want. This means it's not really a good fit for Stack Exchange, so let's take the other answer.
Let's consider that electrons are actually holding still, in real physics. If this is the case, then their momentum is also exactly 0. Due to the uncertainty principle we can state that, if we know their momentum exactly, then we cannot possibly know anything about their position. Their waveform will change such that the electrons could be anywhere in the universe with a relatively uniform distribution (I don't know enough QM to exactly state the limits as momentum approaches 0, it might be uniform, it might be gaussian, it might be another distribution).
Once time resumes, the electrons would be all dispersed to unknown parts of the universe, leaving behind a positively charged object which tears itself apart under electrostatic forces.
Some of these effects can be minimized if you are willing to allow some motion in the slowed area. Then you can calculate how much dispersion of electrons you'll experience based on how tightly you fix their momentum -- the more exacting your limits on their momentum, the larger the uncertainty in their position.
If you scaled it up to atoms, similar effects would occur, except all of the parts of the atom would be dispersed. This makes it far less likely to be followed by a powerful explosion of positively charged matter outwards.