...and the bad
These are some of the worst offenders I've noticed. Reasons for being in the bad list include:
Single items with triangle counts higher than multiple full avatars should use.
VRAM usage for single items higher than an entire avatar should use.
Can have UV maps of 60%+ wasted space, meaning your VRAM gets used for literally nothing.
It is generally a good idea to avoid the following shops in no particular order:
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TonkTastic - Mod - Incredibly high VRAM per item
Catwa - Catwa Clip - No mod heads with incredibly high texture usage. If you use one, never use the teeth version since the teeth alone will add a lot of VRAM usage. 6DOO makes good replacement female teeth, men are out of luck. The heads can be made usable by end users through a lot of texture customization, merge layers to a single image when possible.
Stock Catwa teeth:
Catwa teeth with rescaled textures:
The difference between the two versions cannot be seen under any sort of normal use, but the VRAM use dropped from 16MBs down to 1MB. Unfortunately, the end consumer cannot replace the materials, so the best you can do is drop it down to a bit over 9MBs by rescaling the diffuse texture.
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Melon Bunny - Some of the highest VRAM usage per single attachment you will ever see.
Azuchi - Sands Leavitt - Very high VRAM usage.
DRD - deathrowdesigns | Almost always 200MBs-300MBs+ *per* item. Mod.
Fashionnatic / FN Dress - Ellen Moonites | High triangle counts and VRAM. Example item: Sinder Boots 223.840 triangles and 69,636kb (69MBs) texture memory.
bonbon. - kittynapkitkat | Triangle counts in the hundreds of thousands. Mod.
D-LAB - dazai Voom - Some items are mod.
Addams - Very high VRAM usage.
KC Couture - Very high VRAM usage.
Blueberry - Some older releases are okay, but newe things tend to have very high triangle counts and VRAM usage.
Pure Poison - Very high VRAM usage.
Applefall - warehousefifteendesigns - Very high VRAM usage.
Candydoll - High VRAM for most things.
BREATHE - daisa Admiral
R2 - rei2 Aya | 1024s for literally everything. In the past you could easily reupload all the textures to 256x256 versions and drop the VRAM use by 80%, but they've moved to no mod. Ugh
Code 5 - KellyLingus | Very high VRAM usage. Known content thief. I have personally seen them copy somebody's shape and use ripped textures.
Zenith - Very high VRAM usage.
Cynful - Insanely wasteful UV maps, very high VRAM usage.
RealEvil Industries - Crashnoww Resident - Insane VRAM usage.
-.pr!tty.- - Karla Marama | Insane poly count, very high VRAM usage.
Valekoer - Bob Resident | High polycounts, high VRAM usage. Mod.
eXxEsS - Layja Vidor - Very high VRAM usage.
[ zerkalo ] - Danielestro Resident - Insane VRAM usage. Mod, but you will spend more half the item's price reuploading sanely scaled textures.
enVOGUE Hair - Casandra Rain | Very high VRAM usage.
Just Because - Very high VRAM usage.
Phoenix - 522k triangles for hair. No.
Inkubator hair | marilynmonroe munro - Very high VRAM usage.
DOUX- dam1710 resident - This shop's items are often the sole reason why many male avatars cannot achieve sane VRAM numbers.
*KUNDALA* | Kundala Resident - Very high VRAM usage.
REIGN. | kenadeecole Resident - Absolutely crazy triangle count for their shoes, the highest I've seen in SL.
^.^Ayashi^.^ | Ikira Frimon - Very high triangle counts, high VRAM usage, newer hairs are no mod. Boo.
MINA hair - Mina Nakamura - Very high triangle counts and VRAM usage. Example item: MINA Hair - Raven | Triangles: 475,452 | VRAM: 20,484kb (20MBs)
Truth Hair - Quickly becoming some of the highest triangle count hair in SL due to the awful all in one styles trend.
Mood | Silent Acoustic - Unusably high triangle counts. 800k+ for hair.
[Cosmic Dust] | bodytothestars - Very high VRAM usage. Mod. Example item: {CD&S} - La Lune Cat Backpack: 161,076 tris / 77,824 textures
Taketomi Hair - Bella Ears | 1.4 million triangles in a single hair style due to style options.
Spellbound Hair | Kohana Xue - Insane triangle counts and VRAM use. Example item: +Spellbound+ Bloody Mary, 337,385 triangles, 33,792 VRAM
*katat0nik* - Katat0nik Pidgeon | Very high VRAM usage. Very strict no mod policy.
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If you don't want to be on the bad list, then please learn the basics of efficient modeling. Many of the above shops could easily be on the good list if they would just stop using 1024x1024 textures for literally every single thing.
There are really a lot more shops, but this topic wears me out anymore since nothing ever gets any better.