There could be a way to trick the plugins mentioned in @Jonathan Sampson's answer to do throttling also for your local server.
If you have a high-speed connection and you're behind a modem/router that you are willing to configure (one time set up):
- Add an entry in your hosts file to point localhost to your external IP (that hopefully doesn't change much). You mentioned that you're using virtual hosts. You should add them as well.
- In your router, map external accesses to port 80 (or whatever) to port 80 of your local machine.
- Hopefully, the plugin won't think that the server you're trying to access is on a local IP and therefore won't throttle the connection.
Assuming your external IP doesn't chance all the time (especially if you're in an office with a dedicated line), this solution will help you to use those plugins, with a one-time or one-in-a-while setup in your modem/router.