Port details page requires lots of RAM for hosts with > 100 IP addresses

My php.ini limits RAM to 128MB.
When I try to look at the details page of a host with 511 IP addresses on eth0, the page fails to load and returns a 500.
If I bump the RAM limits to 512MB it renders, and the Apache process consumes 384MB.
Looking into the code, it appears to be coming from includes/print-interface.inc.php, about line 248:
$int_links_v4[$new['port_id']][] = $new['ipv4_network'];
If I remove the "[]" and make the line:
$int_links_v4[$new['port_id']] = $new['ipv4_network'];
Everything seems to work correctly, without needing gobs of RAM to render.

Unrelated to that issue, I observed that for the IPv6 code with the same purpose on line 266, $new['port_id'] is assigned rather than $new['ipv4_network']. I have no idea if this is a bug, but it doesn't fix the memory issue, and doesn't appear to change the page when I remove the "[]".