QUnitMulti` can be turned on upon demand, but the convention for some time in the other Qrack plugins is to turn it off by default, as it tends to hurt performance on Optimus laptops, unless the user intentionally configures a multi-device environment.
The `FSim()` gate has been modified to "aggressively" try to Schmidt decompose its targets before dispatching the gate payload, as with Qrack's C++11 implementation of the 2019 Sycamore ("quantum supremacy") experiment. This is necessary to see maximum "Schmidt decomposition rounding parameter" ("SDRP") actually manage to (vacuously) simulate Sycamore circuits without leading to out-of-memory exceptions, at a baseline. (If SDRP is at its default setting, this should only impose a relatively slight additional execution time cost on the `FSim()` gate, without affecting fidelity.)