Why use jemalloc bundled with Mozilla?

[Mikhail T.]

The system malloc on FreeBSD-10.x is jemalloc-3.4.x. Why do Mozilla ports build
with "--enable-jemalloc" turned on despite that?

Is it just a typo in bsd.gecko.mk and the fix as simple as:

    --- /usr/ports/Mk/bsd.gecko.mk  (revision 390575)
    +++ /usr/ports/Mk/bsd.gecko.mk  (working copy)
    @@ -130,7 +130,7 @@
     
     # use jemalloc 3.0.0 API for stats/tuning
     MOZ_EXPORT+=   MOZ_JEMALLOC3=1
    -.if ${OSVERSION} < 1000012 || ${MOZILLA_VER:R:R} >= 37
    +.if ${OSVERSION} < 1000012 && ${MOZILLA_VER:R:R} >= 37
     MOZ_OPTIONS+=  --enable-jemalloc
     .endif
     

or is there more to it? Thanks! Yours,

    -mi