First off, Mercurial internally treats -everything- as binary. It only makes a
text/binary distinction when asked to diff files or display them in hgweb. So
whatever the problem is, it's not that.

A much more likely situation is that it's simply taking a long time to calculate
or send the delta ("binary" is often synonymous with "huge"). How big is the
file in question? On the Linux side you can use tcpdump or 'watch ifconfig
<interface>' or 'strace -p `pidof hg`' to see if it's still receiving data.