Currently I can play at high speeds, but sometimes the whole thing turns out as a mass.
You can listen my playing at my Soundcloud, on the Crystal Mountain cover I played the solo. I skipped some notes during the solo, only musicians noticed it.

Some information you may need to know:
- On my guitar, the frets are worn out. I'll get a "new" guitar soon, also I'll refret the current one with some quality ones. (the source of flaws?)
- I use economic picking.

Should I start to practice more on my classical guitar (high tension and no distortion to mask minor flaws) or there's a problem with my technique? I have no camera to record it.
Practice more, both with distortion and clean. Make sure you're playing at a speed where you can control what you're doing and make certain you're articulating all the notes well. If you practice well at a low speed it should come through in your faster playing.

Economy picking has nothing to do with it and unless you've been playing for decades on the same guitar I really don't think your frets are the issue either. It's almost certainly a technique issue, you really just need to practice better.

It might help if you consciously exaggerate the articulation while you're playing slowly sometimes to make sure you're hitting all the notes clearly. Still spend the majority of your time playing normally but if you make absolutely certain you're hitting all the notes with good articulation I think you'll sound better.
R.I.P. My Signature. Lost to us in the great Signature Massacre of 2014.

Quote by Master Foo
“A man who mistakes secrets for knowledge is like a man who, seeking light, hugs a candle so closely that he smothers it and burns his hand.”

Last edited by Zaphod_Beeblebr at Sep 29, 2012,
Your timing is sloppy - I can hear you rushing both on the leads and the rhythm parts. It also doesn't help that your guitar tone is a bit muddy and the parts you play are dominated by the existing tracks.

There is no magic bullet, but I suggest you practice the song at a very slow pace - possibly half speed. Make absolutely sure your timing is dead-on. Sloppiness comes from having to really stretch yourself and struggle to keep up, and the fact that you can't play things perfectly at speed means that most likely you can't play them perfectly a bit slower as well. You just need the discipline to keep going and practice more, and eventually it will come.