According to what you said I think your improving, just practice with a metronome at 100 bpm and increase by 10 beats as you progress. 200 to 250 beats is already insane and mind boggling. Very few reach that speed at the same time maintain precision and control like Angelo Malmsteen and Petrucci.
Hold your pick at an angle as Rusty Coley and Francesco Fareri does when picking at hyper speed especialy when tremolo picking if you want to be very fast quickly, but it will make you sloppy. ( No wonder they are SOMETIMES sloppy).
Remember not to sacrifice precision, Its easy to be very fast
but very hard to be fast at the same time maintain control.
I recommend the classic and perfect Yngwie Malmsteen
way of alternate picking which to hold the pick flat in order to be accurate and smooth even at very high speed.
Try this one string passage at 100 bpm to 130
|-14-16-14-13-17-14-16-17-16-14-19-16-17-19-17-16-19---|
|-----------------------------------------------------------|
|-----------------------------------------------------------|
|-----------------------------------------------------------|
|-----------------------------------------------------------|
|-----------------------------------------------------------|
then this at 90 to 120
|12-8---------7-10-7--------7-8-5-------5-7-3-------3-----|e
|-----10---10--------9----9-------5---5-------3---3-------|b
|--------9-------------10-----------5-----------4----------|g
|-----------------------------------------------------------|d
|-----------------------------------------------------------|a
|-----------------------------------------------------------|e
Thats It bro. As the great Frank Zappa said. "There are 3 secrets to master the guitar and that is : "
1)Dedication 2) Practice 3) More Practice!
Marcus Paus practiced 17 to 20 plus hours a day !!
Zakk Wylde said he used to practice 18 hours a day
Vinnie Moore practiced 10 hours a day
Rusty Coley practiced 6 hours a day without miss!
Mark Tremonti practiced 7 hours a day (post Creed > Alterbridge era).
We just know how good they are now. But we did not see the countless hours and years they spent mastering and perfecting their craft.
You to can be like them.....Its just a matter of how dedicated you are and how hard you PRACTICE. I wish you all the best. Peace and ROCK ON !! :)
Guitarplaying is 1 Percent Inspiration, 99 Percent Perspiration... :)