How do you guys do it? Do you guys just make up a pattern or do you have it kind of prepared? I can always have a good lick in my mind, let alone many licks in my mind for my next phrase, but its kinda hard to throw down a good fast lick with improv.
pick out several licks from different songs (dont steal them, just borrow the techniques and practice doing similar things in key with whatever your doing) keep a pocket full of those with different timings ect.. also a good thing to start with, then you'll start to come up with your own.

If you have a lick that will sound good fast, then practice it until you are unbelievably bored, then practice it some more. Over time the amount of practice needed to get a lick up to speed will decrease as you will be used to certain techniques and picking patterns.

Another thing is to improvise, a lot.
It's simply about deciding what sound you want - if you want the sound of a fast run then use one.
Actually called Mark!

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You have to get used to playing all sorts of different interval patterns so that when your inner ear hears a fast run that it wants to play you can do it. In my opinion is you just use stock patterns that you pre prepare beforehand in an improv all the time, then you´re letting your technique do the playing and not your soul. It´s really hard to be able to immediately play patterns that your mind is hearing, but if you can get to that point it is very very worth it.