Should I Install All the PublishPress Plugins?
No, you don't need to install all the PublishPress plugins.
The plugins will not slow down your site, but we find it very hard to imagine a site that needs them all.
The idea is you only install the ones you need. The same is true of most WordPress plugins.
We recommend you take the same approach with PublishPress. Only install an plugin if you need the features it provides. If you're unsure if you need a particular plugin, you're welcome to contact us.