After struggling with getting disconnected from the game very frequently for months, I came across information about Windows 8.1 having internet problems. Indeed, it's possible that my lag coincided with the release of this latest version of Windows. If you search around, lots of people are having intermittent drop outs following the Windows update.

So I'm just putting that out there for consideration. If you're having trouble on PC, it could be a device issue rather than an ISP or game issue. Well sometimes it's those things but diagnosing / tweaking your Windows PC might help too.