You can't run your fast patterns on the guitar as fast as you desire? A very often overseen root cause of your lack of speed is in your mind! You need to be able to process in your mind what you want to hear. You need to visualize it. If you can't hear it in your head, you can't play it (or - if you try to play faster than you can hear, you don't know if you played it well or not - this is not usable and does not count as profound guitar playing). This probably sounds like common sense to you however I know from teaching many people that a shockingly high percentage of guitar players don't do it - they just start to play without connection to their ears. This is why they struggle.
Mental preparation is key. This is critical, don't skip this step. Choose a challenging phrase that you can't play at the desired speed yet (but slower you can). Play it, but wait: before you play any note, image in your head how it sounds when it's played correctly - at a speed you feel comfortable with right now. Can you really imagine it? Can you hear it in your head? Can you feel it without physically playing it?
When you got this: now play it on the guitar. Play it a few times to make sure that this is at a speed that you can reliably play your phrase, and tap the beat with your foot. Make sure that the timing of what you play matches the beat that you tap. Then stop playing but continue to tap your foot - without changing the tempo. Grab a metronome and tap the beat to get the bpm number. Write it down. Re-check: put on the click and play your lick over it. Reminder: don't forget to hear it in your head first before you play!
Here is what you can do to get faster by expanding your mental comfort zone: picture yourself playing your phrase a bit faster! Set your metronome to a tempo that is slightly higher than what you measured in the step above. Put on the click and visualize yourself playing it. Focus. Really imagine it, hear it, feel it. If you have a clear vision in your head of what you want to hear, then set it back to your tempo where you already felt comfortable with and play it. It will likely feel already a bit easier. Now set the metronome back to the higher speed and visualize. If you do well, you can even increase it a bit more and see if you still can visualize it. Then again go back to your comfort zone tempo and play it. Repeat this cycle a few times. You will probably feel the urge to increase the metronome for playing it on the guitar - but resist for now and repeat the cycle a few times (when you come back to play it on the guitar you go down to your comfortable speed from above). AFTER you have actually done this, then try to actually play it to a tempo that is slightly faster. If you don't make too big jumps, you'll likely achieve some progress in just 1 practice session. Now imagine how far you can get if you did this on a regular basis. Have fun in the process of becoming a shredder!
Lutz Richter is a professional guitar teacher in Potsdam, Germany who successfully helped many people to get mentally ready to shred.