Rearrange the channel buffer sizes into three neat use-editable values in options.h. Increasing RECV_MAX_WINDOW gives big network performance increases - even with the present buffers (which haven't changed) it performs a lot better. Next step is to make the window size a cmdline option.

open(IN,"<crypt.ind");
open(OUT,">crypt.ind.tmp");
$a = <IN>;
print OUT  "$a\n\\addcontentsline{toc}{chapter}{Index}\n";
while (<IN>) {
   print OUT $_;
}
close OUT;
close IN;
system("mv -f crypt.ind.tmp crypt.ind");