This is a true stuggle for me, Whenever I ever try playing a fast rock song, like some songs by Avenge Sevenfold (holy Jesus they're kinda insane for me, really awkward rythms they have. I get the beat right, but whenever it comes to those really tight, small pauses where it's a sweet point for a fill, I always screw over, and I flood over the fill, masking the timing.  I mean I go way off beat, and I have to wait and listen before startin again, I've tried doin a simple 16th note cycle with the toms and snare, and the classic snare 32nd roll.  But, I've been wantin to rack up some more fills to make it not sound like I'm playin the same thing over and over again, including on them 5-minute songs.  Also, I've been trying to figure out more fast rock rythms other than the common 8th not bass, 8th note snare.  I've forgotten the Chelsyea beats (I even forgot part of the name) . But if any could lend some tips it'd be appreciated.

I once had an instructor tell me to stop practicing drumming and practice being a drummer. I think he meant sometimes you just have to sit down and work out the guilty pleasures of drumming, such as getting around the kit in bombastic way.

Very simple exercise that should help you:

While keeping time with your left foot hi-hat, play eighth-notes from snare down your tom line and back. If that feels good, kick up the tempo.

Graduate from eighth notes to sixteenth notes to 32nd notes around the kit. If you do that every day for six months, you should be able to handle the basic "fast rock fills" that come your way. But if you REALLY want to enjoy this, take the same exercise and break it up. Change which drums you fill on, alternate between sixteenths, triplets, eighths, 32nds. That's the kind of experimentation with a simple exercise that will really help you get around the kit, and you probably will want to use more of your own fills rather than someone else's.

Dude..playin fast is not going to mean anything if u don't add some flavor to the fills. Try this first: practice the different rudiments at a slow tempo. Then try different combinations with the rudiments. After that increase the tempo at which to practice. Oh, I almost forgot to say try including the bass drum in ur fills and like smoggrocks said...adding the hit-hat in between makes sound even sweeter or any cymbal during the fill for that matter (it not only adds flavor but it adds some form of complexity to it ). So as i said at the start, don't worry about playin fast...cause i took me a while before i could play 32nd notes at 150bpm...and all that speed and control ment nothing if i didn't have some form of variety. (At least this is my opinion on what u should do.)

That's great advice.