I was averaging 40 K/sec upload speeds to Squarespace, and then I found this information from Google on configuring your network settings to use Google Public DNS. Now I'm averaging 120 K/sec. It's still not great, but I'll take what I can get!
Here's the scoop:
When you use Google Public DNS, you are changing your DNS "switchboard" operator from your ISP to Google Public DNS.
In most cases, the IP addresses used by your ISP's domain name servers are automatically set by your ISP via the Dynamic Host Configuration Protocol (DHCP). To use Google Public DNS, you need to explicitly change the DNS settings in your operating system or device to use the Google Public DNS IP addresses. The procedure for changing your DNS settings varies according to operating system and version (Windows, Mac or Linux) or the device (computer, phone, or router). We give general procedures here that might not apply for your OS or device; please consult your vendor documentation for authoritative information.
Note: We recommend that only users who are proficient with configuring operating system settings make these changes.
After the jump: Configuring your network settings to use Google Public DNS