Astral, that's weird you're having these problems. Which version of windows are you using and are you sure it's HackShield? It might be anti-virus software, or maybe your rig just isn't powerful enough for dx11 (dx11 has a memory leak and is poorly optimized). Try changing the client to dx9. Some people with lots of ram have also been using RAM disks and running Archeage from it.
I'm absolutely sure it was HackShield, as no other process was doing disk writes. Slowed my computer down to a crawl due to constantly using the HDD until I restarted, but at least it wasn't killing my SSD with constant writes.
And if my Windows 7 system isn't beefy enough to run DX11, I've been doing it wrong for the past few years. The SLI'd nVidia GTX 560s may need an upgrade in a year or two, but those with the i7-3820 (4 x 3.6 GHz cores) are more than enough to handle any game for a while to come.
I seem to have fixed it by a suggestion noting that Windows Firewall won't automatically add exceptions to both the game and Glyph, so manually adding them seems to have fixed the problem. Hackshield is still a piece of crap though. It won't stop someone determined to undermine their game, and for the two hours I was able to get in before a server maintenance (with 3500 and over an hour queue for two hours... at midnight on a week night, eastern time), I noticed way too many gold/hack/advertising bots.