  The Laser Interferometer Space Antenna (LISA) is a future space-based
gravitational wave (GW) detector designed to be sensitive to sources radiating
in the low frequency regime (0.1 mHz to 1 Hz). LISA's interferometer signals
will be dominated by laser frequency noise which has to be suppressed by about
7 orders of magnitude using an algorithm called Time-Delay Interferometry
(TDI). Arm locking has been proposed to reduce the laser frequency noise by a
few orders of magnitude to reduce the potential risks associated with TDI. In
this paper, we present an updated performance model for arm locking for the new
LISA mission using 2.5 Gm arm lengths, the currently assumed clock noise,
spacecraft motion, and shot noise. We also update the Doppler frequency pulling
estimates during lock acquisition.
