They aren't faster in the cases I know of. As an example, the Isle of Man TT Zero was discontinued partially because 2008 predictions of electric bikes reaching parity with gas by 2025 didn't pan out.

Even for small stuff, a minibike with a 212cc 4-stroke can have comparable performance to something like a Cake or Surron and is a fraction of the cost.

Personally I think the electric motorcycle market should try and max performance versus weight. Perhaps something pedal assisted that could hit 60 mph without too much fuss but light enough that it could be shouldered up a few flights of stairs. Range can be low, as in 10-15 miles per charge max but balanced by swappable battery packs.