In the
wiki's Lightning Feats standards, for a non-cloud-to-ground electricity attack to be assumed to be at the speed of cloud-to-ground lightning, the attack needs to display a few properties of real-world electricity (not an issue here) AND be done by a character capable of producing 1.6 billion Joules attacks (around 8-C) or a voltage of 100 million Volt.
Electro is at Wall Level, and canonically can hold a maximum of 10,000,000 Volt, so he doesn't fulfill the second condition.