Moreover what we know from the physics of our current general purpose quantum gates (different rules apply for quantum annealers like the D-Wave but these cannot perform Shor's algorithm) it is unlikely it will take more than that to perform a computation. Quantum states in circuits decohere quite rapidly; this is the main obstacle we face in developing them. Chances are we won't have a choice but to do things relatively quickly with quantum computers (there are some possibilities where we need to take time to prepare resources for the computation, but these have the advantage of being trivially parallelizable).
On the plus side, all quantum algorithms will be unable to perform a Logjam-style attack[1] where you do part of the computation once because the same parameters are reused by many servers. You can't copy quantum memory in any useful sense.
On the plus side, all quantum algorithms will be unable to perform a Logjam-style attack[1] where you do part of the computation once because the same parameters are reused by many servers. You can't copy quantum memory in any useful sense.
[1]: https://weakdh.org/