&gt; Quite a lot of things.<p>I don&#x27;t think that&#x27;s fair to say. grsec provides many things. Some are completely transparent once implemented, (readonly variables) some have performance impact, (uderef on 32bit) some (purposely) break existing behaviour. (forbidden MSR writes prevent energy management)<p>You can pick and choose what you want. In practice on new hardware, I don&#x27;t see any big drop in desktop environment.