Extensions slow down Firefox so I prefer disabling all but the most important Firefox extensions when coding.
Here's how to do it:
1. First, create a development profile following these instructions
1. Next, create a shortcut that starts Firefox in development mode:
```bash
# Mac OSX
/Applications/Firefox.app/Contents/MacOS/firefox-bin -P development -no-remote
# Linux
/usr/lib/firefox/firefox-bin -P development -no-remote
# Windblows
"C:\Program Files\Mozilla Firefox\firefox.exe" -P development -no-remote
```