EDIT: Gwyneth Llewelyn, who is a lot smarter than me, wrote a much better post about lag. But I still stand by what I say for myself because I know it helps me out. :) Your mileage may vary, of course!
If you are attending Hair Fair 2008 today for opening day, here's a few things you can do to help yourself and help EVERYONE. If you've never been to one of these things before, you need to pay close attention. Those of us who have gone to any of the expos or any of the treasure hunts already know the rules. You are about to enter into lag like you may never have had before.
1. Go in texture clothes only, or maybe with only a small prim attachment. Do NOT show up in a damn ballgown with 40 layers of flexiprim. No one is looking at you, and if you show up in that, the only reason people will be looking at you is to glare at you for being dumb enough to wear that much flexi in a place that is lagged out.
2. No super primmed shoes or accessories!! You may think you look fierce in your 250 prim boots, but you don't. You're not at the club. You're at a VERY laggy place hair shopping. There's no need for it. In fact, just go barefoot. Use the lowest prim hair you have in inventory, or...just go bald! Hey, it's Hair Fair! You'll get some more!
3. Sorry ladies, but you gotta take those AOs off. In fact, take everything scripted you own off. The lag is so bad, you couldn't tell a sexy walk from a noob walk anyway. And take off any of your facelights, radars, weapons, items with bling, or pretty much anything with some kind of script.
4. No poofers. C'mon, that's just common sense.
5. It's going to be slow to rez, so when you show up, walk politely to the side and wait for things to rez. Don't just go barreling through like a bull in a china shop, because a lot of people get bothered when someone smashes into them.
6. Speaking of polite - use good manners. Refrain from using many gestures [or any gestures], especially if they chat spam or make noise. Don't yell about how someone's hair sucks. The designers have put a lot of working into making NEW hair for Hair Fair [unlike at some of the other fairs/expos this year where there wasn't much new at all] so be polite. Maybe you don't like it, but someone else might. Maybe it's not really great quality, but...well, they might not know that. If you see a designer, thank them for their work, especially if they've put out a free gift. Gifts are not a right, they are a privilege.
7. Slam your draw distance down as low as you can. This is more for your benefit than anyone else's. 64m is much less of a lag to you than 512.
When in doubt, just use common sense. As residents of SL, we all know what lags and what doesn't. By doing just a very few simple things, you can make the experience better for yourself and for your fellow residents. :)