As for Firefox, the op has already answered his own question (Menu – Web Developer – Network or Ctrl + Shift + K – Network or Ctrl + Shift + Q), but I’d like to mention the “app.telemetry Page Speed Monitor” addon, which does not require you to open the web console first. It’ll just show the load time in ms in the status bar (it’ll even show details when you click it).
https://addons.mozilla.org/en-US/firefox/addon/apptelemetry/
The only downside seems to be the Facebook/Twitter button.
As for Chrome/Chromium, I second Andy Davies’ suggestion, the Page load time plugin is awesome, it shows the load time next to the location bar and it also provides details.