Toolbelt cleans out some core WordPress features for you. They're little things that aren't used by most sites. There's no harm in having them, but by removing them we:
- Remove some of the html in the header.
- Reduce the overhead of generating the content.
Personally, I like to remove the features since I don't use them. If you don't want to do this or need some of the features then feel free to disable the module.
WordPress Features Disabled/ Changed
- Remove Really Simple Discovery (RSD) links. They are used for automatic pingbacks.
- Remove the link to wlwmanifest.xml. This adds support for Windows Live Writer.
- Remove generator tag from RSS feeds.
- Remove the next and previous post links from the header.
- Remove the shortlink url from header.
- Remove WordPress generator version.
- Remove recent comments widget style.
- Remove emoji styles and script from header.
- Slow down the default heartbeat to 60 seconds.