Well, that's a very broad question. There are literally hundreds of thousands of Wordpress plugins, many of which don't have a significant impact on page speed.
But if you load your site up with unnecessary plugins for features and functionality you don't need, the accumulated mess could slow down your site even if none of the individual plugins is a problem on its own. Not to mention the potential security risk having all those unnecessary plugins could present.
What do you want plugins to do
, specifically? Narrow down the field of what exact kind
of plugins you're looking for and we might be able to give you some reasonable recommendations.
Sorry, but as it is, your question is unanswerable.