Faster Circuit.zip and Circuit.append

[NoureldinYosri]

Is your feature request related to a use case or problem? Please explain

using Circuit.zip and Circuit.append is a common code pattern and optimizing them will increase the performance of a lot of operations (e.g. transformers)

P1 – I need this no later than the next release

P2 – we should do it in the next couple of quarters

P3 – I'm not really blocked by it; it's an idea I'm proposing based on principle

[pavoljuhas]

Cirq cynq meeting - @NoureldinYosri - can you please provide some concrete examples where Circuit.zip and Circuit.append are the choke points? This would be helpful for creating a benchmark and having a quantitative measure for optimizing these functions.