yescrypt improved scalability

Scalable from kilobytes (RAM) to terabytes (ROM) and beyond
while providing adequate security vs. alternatives for same defender's {time, memory} cost
Configurable entirely via runtime settings
A read-only lookup table (ROM) can be arbitrarily large regardless of running time
This differs from scrypt, where memory usage for a given running time is limited, so scrypt's memory usage might not be high enough when high request rate capacity is desired (16+ MB may be hard to achieve at thousands of requests per second)
Scalable to arbitrary SIMD vector width and instruction-level parallelism
To be configurable via compile-time settings, or chosen at runtime from common presets
Current defaults are for 4x 128-bit SIMD lanes (512 bits)
scrypt's p could be brought down to instruction level, but it would be sub-optimal