  While intensively studied, it remains unclear how the star formation (SF) in
Infrared Dark Clouds (IRDCs) compares to that of nearby clouds. We study
G351.77-0.53 (henceforth G351), a cluster-forming filamentary IRDC. We begin by
characterizing its young stellar object (YSO) content. Based on the average
parallax of likely members, we obtain a Gaia distance of $\sim\,2.0\pm0.14$
kpc, resolving the literature distance ambiguity. Using our Herschel-derived
N(H$_2$) map, we measure a total gas mass of 10200 M$_{\odot}$ (within 11
pc$^2$) and the average line-mass profile of the entire filament, which we
model as $\lambda =~1660 (w/\rm pc )^{0.62}\,\,M_{\odot}\,\rm{pc}^{-1}$. At $w
< 0.63$ pc, our $\lambda$ profile is higher and has a steeper power-law index
than $\lambda$ profiles extracted in Orion A and most of its substructures.
Based on the YSOs inside the filament area, we estimate the SF efficiency (SFE)
and SF rate (SFR). We calculate a factor of 5 incompleteness correction for our
YSO catalog relative to Spitzer surveys of Orion A. The G351 SFE is $\sim 1.8$
times lower than that of Orion A and lower than the median value for local
clouds. We measure SFR and gas masses to estimate the efficiency per free-fall
time, $\epsilon _{\rm ff}$. We find that $\epsilon_{\rm ff}$ is $\sim$ 1.1 dex
below the previously proposed mean local relation, and $\sim\,4.7\times$ below
Orion A. These observations indicate that local SF-relations do not capture
variations present in the Galaxy. We speculate that cloud youth and/or magnetic
fields might account for the G351 inefficiency.
