ptmalloc is the original version of the malloc that was later included
in GNU libc.  Under some circumsntaces, notably with pthreads and
excessive calls to realloc, it performs significantly better than
FreeBSD malloc.  This version is *not* GPL or LGPL:

  Copyright (c) 1999 Wolfram Gloger
  
  Permission to use, copy, modify, distribute, and sell this software
  and its documentation for any purpose is hereby granted without fee,
  provided that (i) the above copyright notices and this permission
  notice appear in all copies of the software and related
  documentation, and (ii) the name of Wolfram Gloger may not be used
  in any advertising or publicity relating to the software.
  
  THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
  EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
  WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
  
  IN NO EVENT SHALL WOLFRAM GLOGER BE LIABLE FOR ANY SPECIAL,
  INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY
  DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY
  THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  PERFORMANCE OF THIS SOFTWARE.

This is not the latest version: it's older than the one in GNU libc.
There is a newer version, but it's still marked as "current snapshot".
It's in /usr/ports/devel/ptmalloc-2/.

See the web site for more details: WWW: http://www.malloc.de/en/

This package comes with no documentation beyond a README, which isn't
worth installing.  It appears that the GNU libc man page malloc(3)
applies, but it's not included here for copyright reasons.  There's
nothing unusual about it.  In particular, the section TUNING in
FreeBSD malloc(3) does not apply.

This library uses the POSIX pthread_atfork() function which was not
committed to -CURRENT until 10 December 2004.  See PR bin/68841 for
further details.  To build it on older versions, first install this
patch, which should be transparent.

In addition to the library, the package contains a couple of test
cases.  Theoretically they could be run using the FreeBSD libraries,
but they call the legacy memalign() function, which is not provided by
FreeBSD.  It may be of interest to fix this issue.