  Lattice surgery is a measurement-based technique for performing
fault-tolerant quantum computation in two dimensions. When using the surface
code, the most general lattice surgery operations require lattice
irregularities called twist defects. However, implementing twist-based lattice
surgery may require additional resources, such as extra device connectivity,
and could lower the threshold and overall performance for the surface code.
Here we provide an explicit twist-based lattice surgery protocol and its
requisite connectivity layout. We also provide new stabilizer measurement
circuits for measuring twist defects which are compatible with our chosen gate
scheduling. We undertake the first circuit-level error correction simulations
during twist-based lattice surgery using a biased depolarizing noise model. Our
results indicate a slight decrease in the threshold for timelike logical
failures compared to lattice surgery protocols with no twist defects in the
bulk. However, comfortably below threshold (i.e. with CNOT infidelities below
$5 \times 10^{-3}$), the performance degradation is mild and in fact preferable
over proposed alternative twist-free schemes. Lastly, we provide an efficient
scheme for measuring $Y$ operators along boundaries of surface codes which
bypasses certain steps that were required in previous schemes.
