Slow connection after upgrade and fresh Win7 install

[Darklurker]

So, yesterday I upgraded my PC, installing a Z87-Plus and i5 4670k, along with a fresh Win7 Ultimate x64 install. But now my internet connection is extremely slow (it's wired). Online tests put it at about 1.5Mbps, and my downloads are peaking at a few dozen Kbps.
I have already tried upgrading all my drivers, my chipset and so on, and some other suggestions I've read online (disabling QoS and IPv6, disabling IPv4 checksum offload), but to no real avail.
Any ideas, guys?

[Deleted]

Have you installed the 1/2GB+ of Windows Updates yet? Or maybe you ran the speed test while Windows was downloading the updates?

[Darklurker]

I installed it with SP1 already, so I didn't have that much stuff to download still. But yes, it's fully updated. I have ran tests for a lot of scenarios now (several network adapter settings, with and without firewall, etc.). My upload speed is correct, I have to add. But download ranges from 1.5 to 3 Mbps, should be 15.

[Jacus]

turn off the Network IControl in the AI Suite II

[Darklurker]

turn off the Network IControl in the AI Suite II

I didn't install the AI Suite, or any of the other "utilities". Drivers only.