picking hand speed
fretting hand speed
and co-ordination
you seem to have the picking hand speed, this can be developed by tremelo picking, as you have done.
but you dont seem to have mastered the other two.
fretting hand speed is best improved by practicing legato, (as has been suggested)
lastly co-ordination. only atttempt this when you are satisfied with the speed of each hand independantly. then practice this.
sadly there is no quick fix, you have to put the work in. if you are serious abou this i suggest you give yourself certain exercises spend about 5 minuets and each. then come back to it several times in the day.
anyway good luck and keep practicing.
EDIT: all above stuff done with a metronome. starting at a pace you are comfortable with and slowly movin it up.