  The Rapid Iterative FiTting (RIFT) parameter inference algorithm provides a
framework for efficient, highly-parallelized parameter inference for GW
sources. In this paper, we summarize essential algorithm enhancements and
operating point choices for the RIFT iterative algorithm, including choices
used for analysis of LIGO/Virgo O3 observations. We also describe other
extensions to the RIFT algorithm and software ecosystem. Some extensions
increase RIFT's flexibility to produce outputs pertinent to GW astrophysics.
Other extensions increase its computational efficiency or stability. Using many
randomly-selected sources, we assess code robustness with two distinct code
configurations, one designed to mimic settings as of LIGO O3 and another
employing several performance enhancements. We illustrate RIFT's capabilities
with analysis of selected events.
