From this question and Sander Mangel answer:
First of all, less modules means less code to (potentially) load and process. Next to that, a lot of modules, like for example the Mage_Rss module run a lot of code in the background like forcing reindexes on certain events.
Because the above question was not directly meant to share a module list I think is a good idea to collect info here.
Other useful Resources:
Any other module suggestion ?
Which module has more impact in performance?
An update list with @Marius suggestions
- Mage_WishList - looks it break customer details
- Mage_Tag (when not used in a project)
- Mage_Poll (cause who uses polls anyway)
- Mage_Rating ( if not required by client)
- Mage_Bundle ( if not required by client)
- Mage_Downloadable ( if not required by client)
- Mage_GiftMessage - looks you need it in 1.8 or product details will break
- Mage_XmlConnect - if you don't have / need a mobile app.
- Mage_Paypal (if not used as a payment method)
- Mage_Paygate (Only if you disable Mage_Paypal, Mage_PaypalUk and Mage_Authorizenet)
- Mage_Weee (only if you disable Mage_XmlConnect also)
- Mage_Usa - only in ce-184.108.40.206. (see below why)
- Mage_GoogleCheckout - can only be disabled in ce-220.127.116.11 and only if you disable Mage_Usa. It doesn't work for previous versions because of this http://www.magentocommerce.com/bug-tracking/issue/?issue=14359
- Mage_Oauth - if you don't need the REST API
- Mage_Api2 - only if you disable the Mage_Oauth also.