Grass shadows since patch 1.5 are buggy, hurt performance and can't be disabled. That's three negatives.

1. Bugginess:
Grass shadows look good in sunny weather with bright lighting. But as soon as there is dark lighting, for instance during foggy or rainy days, grass shadows look awful. They are way too dark.
You can see it here: http://www.youtube.com/watch?v=HrnxpTcUvPQ

2. Hurt performance:
Grass shadows costed me at least 5-8 FPS, and that's pretty much for something so little. Of course, more shadows cost performance, and that's not the issue here. The issue is that some people can't spare 5-8 less FPS, but there is no way to disable grass shadows. Thus grass shadows hurting performance for ALL users. That's really bad.

3. Can't be disabled:
Grass shadows can't be disabled. A lot of people have been saying put "bShadowsOnGrass=0" under [Display] section in both Skyrim.ini and SkyimPrefs.ini. Well, let me enlighten those people who have been saying that that it does not work. So in short, we have no way to disable grass shadows.


Conclusion:
The grass shadows are buggy since they are way too dark at dark lighting conditions, making them look really ugly. At the same time the grass shadows cost many FPS and hurt performance.
Finally, and the worst part, they can't be disabled. This is especially bad considering the other two negatives mentioned above.
Bethesda you should really, really do something about this for the next patch. I appreciate new features, it's nice of you Bethesda, but it's not a good idea to implement new features that are buggy and hurt performance, and then have no way of disabling them, thus forcing all users to suffer from it no matter what.

Agreed. Had to drop all my sliders since 1.5 to keep gameplay smooth. I know OpticShooter asked the Community Manager, Matt, about the issue a few days ago. Hopefully some good news will pop up.

Agree as well. I don't really see the need for a feature that is easily unnoticeable when off. I hope they give the option to turn it off in the future.

Totally agree. I think it's ace they are adding new features in patches like much much better underwater effects and shadows on grass etc. but if something hurts performance, it should always be optional for the end user.

Strange i have no issues with grass recive shadows they work fine for me , here are all my shadow settings in my ini if you weant to try them for a fix :-

[Display]
iBlurDeferredShadowMask=4 (set to 0 for AO to work )
fShadowDistance=5000.0000
iShadowMapResolutionSecondary=512
iShadowMapResolutionPrimary=1024
iShadowSplitCount=2
fShadowLODStartFade=200.0000
iShadowMode=3
bGrassReceiveShadows=1
bShadowsOnGrass=1
bShadowMaskZPrepass=0
iShadowMapResolution=2048
fShadowBiasScale=1.0000 (set high to fix shadow lines on rocks)
iShadowMaskQuarter=4
iShadowFilter=3

[Grass]
iMinGrassSize=20
b30GrassVS=1
fGrassStartFadeDistance=20000.0000
fGrassMaxStartFadeDistance=20000.0000
fGrassMinStartFadeDistance=0.0000

Make sure you look at the grass shadows during foggy or rainy weather.
They look fine during clear and cloudy weather. If it looks OK then as well, then you're a lucky exception for some reason. It does seem to look awfully dark for (from what I can tell) 99% of all other users...

It seems the grass shadows introduced stuttering on my box. I'd love to have ability to disable this feature.

You're lucky you only lose 5-8 FPS, I lose upwards of 30 in dense forest areas. I used to get 45-50, but because of the shadows on the grass it just plummets now. Really hoping for an option to disable this feature in the next patch.

For something that has such little effect on the visuals of the game the performance hit on this is way too much. I was much happier without the grass shadows. I agree that this should be optional or even taken completely out in the next patch. I didn't notice it when it wasn't there and I won't miss it when it's gone.

You ungrateful whelps! They force you to accept a broken feature that you didn't ask for and this is how you show your appreciation? By complaining?

I haven't noticed any of the issues reported in this thread. I'm not saying they're not present, but I certainly haven't noticed them.

I have the black grass mainly in tree rich environment: there where the shadow of the trees hits the grass, the grass is just pitch black. But also somehow sometimes in snow areas, there also is a big change of the black grass.

I have noticed a frame rate drop since the 1.5 update. Downgraded my resolution and then adjusted the sliders when that didn't help. I used to be able to have everything to maximum and my resolution was at 1920 x 1080. Now sliders have been adjusted and resolution is 1400 x 900. I have noticed a high frame rate drop in wooded grassy areas still but wasn't sure what it was. Bethesda please fix this grass shader issue, thanks. And please for future reference if something is working don't fix it. The game was working on my machine perfectly before grass shaders were added. I won't miss them.

Just adding my voice to the choir, the grass shadows are giving me a bit of slowdown in the swamps beneath Solitude, it's made many times worse with supersampling AA, 20fps on a PC that did a solid 60fps pre patch, definitely buggy behaviour

All in all I've found 1.5 to be crash prone and maybe a bit more stuttery with cell loading, I'm using the latest Forceware beta 301.24 as well, don't know if that relates to the supersampling slowdown or not.

*edit*

Did a quick bit of testing and reverted to 1.4.27, performance hit has gone and loading stutter is reduced, didn't test long enough for crashes though, it's a shame because I really like the new features, especially the underwater effects and better snow LOD blending.

Any news on a fix for this with the new 1.6 beta?

Nothing specific in the changelog, unless it somehow falls under the vague umbrella of "general stability and memory optimizations." I wouldn't hold my breath, unfortunately.

I'd test the beta myself, but I'm not experiencing a huge performance hit from grass shadows and have a bunch of mods that would get in the way of testing properly, so my game isn't exactly the best test bed. I do have a friend with performance issues and shadow glitches from the 1.5 update, though...I'll have to see if I can, uh, "volunteer" her for testing the beta patch later.

Yeah I'm not to keen on updating just yet, my install of Skyrim is quite stable...don't wanna poke the monkey.

According to another thread the grass shadows are still non optional...bah

*edit*

Someone has pointed out to me that a new option has appeared in the prefs ini, bShadowsOnGrass apparently disables the grass shadows, yay

This is great news, however, i'm not seeing the bShadowsOnGrass command in the prefs ini. Is this something that I need to add myself?

It should be added automatically, at the bottom of the [Display] section, if you've updated to the 1.6 beta. You may have to start the game at least once too.

It looks like this to me now:

iPresentInterval =1
iShadowFilter =3
bTransparencyMultisampling =0
bDrawShadows =1
bShadowsOnGrass=1
bDeferredShadows=1

Ahah! Thanks a lot, this is a 1.6 beta implementation.

a common work around is to turn down the grass view distance (3-4 should work).

it's a commonly known issue post-1.5.

edit: also, don't try to do this in-game. the lag will still be present until you actually MANUALLY restart the game.

Could someone confirm that disabling the grass actually works? People have been throwing around these useless .ini settings several weeks, including the very same setting people now say are added.
It would be nice if someone with the problem tried this apparently new .ini setting and confirmed that it actually works!

If it indeed can be disabled now, then very good
That would mean I can play Skyrim again and enjoy it. The lag has killed the joy so far.

Confirmed. I opted into the beta, loaded the game, went to a spot where I could see very obvious shadows on grass, saved, quit, and set bShadowsOnGrass=0 in the SkyrimPrefs.ini. Reloaded and tada--no more grass shadows.

It's possible that ini setting wasn't working in 1.5, but it works now in 1.6. For which I am very happy.

Thanks (and thanks Bethesda)! Will be waiting for the non-Beta version with great anticipation then!