errr, we use tcmalloc from ports (devel/google-perftools/):
solko@[zmail /usr/ports/devel/google-perftools] # ldconfig -r | grep tcmalloc
121:-ltcmalloc_minimal.0 => /usr/local/lib/libtcmalloc_minimal.so.0
122:-ltcmalloc.0 => /usr/local/lib/libtcmalloc.so.0
124:-ltcmalloc_and_profiler.0 => /usr/local/lib/libtcmalloc_and_profiler.so.0
obviously, i forgot to include patch for libexec/zmslapd. dunno, how that slipped through

.
from 601:
diff -uNr GNR-601.orig/ZimbraServer/src/libexec/zmslapd GNR-601/ZimbraServer/src/libexec/zmslapd
--- GNR-601.orig/ZimbraServer/src/libexec/zmslapd 2009-04-10 00:54:02.000000000 +0200
+++ GNR-601/ZimbraServer/src/libexec/zmslapd 2009-09-16 08:10:36.000000000 +0200
@@ -16,5 +16,12 @@
ulimit -n 32768
ulimit -c unlimited
-export LD_PRELOAD=/opt/zimbra/tcmalloc/lib/libtcmalloc_minimal.so
+
+PLAT=`/opt/zimbra/libexec/get_plat_tag.sh`;
+
+if [[ $PLAT = "FreeBSD"* ]]; then
+ export LD_PRELOAD=/usr/local/lib/libtcmalloc_minimal.so
+else
+ export LD_PRELOAD=/opt/zimbra/tcmalloc/lib/libtcmalloc_minimal.so
+fi
exec /opt/zimbra/openldap/sbin/slapd "$@"
i will fix that someday.. me be sorry.