long delay with binary data on ubuntu and 9.4.1

When executed in psql on Ubuntu 14.04 LTS (ubuntu/trusty64) the query "select bindata from rcfiledata where id = 106" hangs from 6-12 seconds before completing. On OS X, it takes a few milliseconds. This happens with the package available from postgresql.org for 9.4 and with a compiled version of 9.4.1.

All tests were with the server running on OS X. Ubuntu was running in vagrant/virtualbox. The attached filedata.sql contains a dump of the table.

The same problem happens when executed in a program using libpq.That program is included in pgtest.c. When breaking in gdb while hung, the backtrace is:

(gdb) bt
#0 0x00007ffff72ab110 in __poll_nocancel () at ../sysdeps/unix/syscall-template.S:81
#1 0x000000000040bb9e in pqSocketCheck ()
#2 0x000000000040c480 in pqWaitTimed ()
#3 0x000000000040a809 in PQgetResult ()
#4 0x000000000040aafe in PQexecFinish ()
#5 0x0000000000402c4b in main (argc=1, argv=0x7fffffffe648) at pgtest.c:9