From Krebs on Security:
If you’re the type of person who uses multiple extensions, it may be wise to adopt a risk-based approach going forward. Given the high stakes that typically come with installing an extension, consider carefully whether having the extension is truly worth it. This applies equally to plug-ins designed for Web site content management systems like WordPress and Joomla.
The only extensions I use these days is an ad blocker (1blocker), add to instapaper, 1password and a rss subscribe button. Most everything else gives me the creeps when you read what it actually needs access to.