If you are in a rut with whatever your are practicing for speed i.e. diatonics, pentatonics, arpeggios etc., move your practice routine to something different. Your mind has built some sort of self-governor that thinks it cannot go any faster, when in reality, it can.
I suggest diving into pentatonics if you have been beating on diatonic scales and/or arps. If you have been working on pentatonics, then try octave displacement,
string skipping, or any other wide intervallic leaps. The point is, distract your "governor" with something that is completely different. Once you have mastered, or at least gotten relatively good at that "different" then try going back to your previous practive regimen. Often you will find that your mind dropped whatever was limiting it.
Also explore your picking/right hand technique. You may very well be setting some sort of physical limitation with your right hand. Explore anchoring vs not anchoring, circular picking, alternate/sweep picking, even hybrid picking/finger picking. Often your right hand will be very natural at something you didnt even know it could do.
Hope this helps, and by all means go outside an enjoy the world around you.