Keep in mind that the firmware on the Almond+ is loaded into RAM, so the full 512MB isn't available.
Below is the output from "top" at the command line
Mem: 432392k total, 114672k used, 317720k free, 11564k buffers
Should still be plenty available memory though as we seemingly have some 300MB left to go around.
Also, we have a 750MHz dual core, not a 1GHz. That said, once all the driver work is done, courtesy of a network offload co-processor, the Almond+ will be using very little of the Cortex-A9 part of the SoC when it comes to handling any kind of network traffic, unlike most routers where a large chunk of the CPU is used to handle the network traffic.
As a quick example, I was testing some stuff the other day and used an Asus RT-AC66U which was using 50%+ CPU whereas as the Almond+ was using 15-20%+ doing the same thing and that's without the offload being fully implemented.