Since the 1.5 patch I (well, Skyrim ) suffer from massive drops in fps when going from a indoor scene to a outdoor scene, it is suddenly 15 fps. I have to do the Alt/Tab action to get my normal 50-60 fps back. This happens now 7 out of 10 times when I go from in- to outdoor
I did uninstall everything and made a totally clean install of everything: a 100% vanilla version, no tweaks, no mods. But still those massive fps drops.
What I can see with MSI Afterburner (just for monitoring, no overclocking) is that after a cutscene when I open a door to go outside, my graphics card memory is suddenly completely full (1008 Mb where it is normally around 850 Mb) and my graphics card GPU is at 100% (where it normally around 90%). After the Alt/Tab action it all is back to normal. Everything else looks normal: temperature is and stays around 55 degrees Celsius, no weird things in the Core voltage, and so on.
I know this has been covered before and probably a bug in the 1.5 patch, but maybe some new information/tips are there now to get rid of these huge fps drops?

Does this also happen when you wait or sleep in game?

Because I remember I had the very same issue in fallout 3 then again in fallout new vegas but both were fixed by doing a "clean install" of my graphics card drivers.

Isn't the fps drop normal going outdoors as there is more demand on rendering the scenes?

@ oblivionjosh
No, waiting or sleeping is no problem, just normal fps after that. It's only when going from indoors to outdoors.

@ USA
A little fps drop is normal. But not from a normal 55 to 15 fps and then staying at 15 fps. Only the Alt/Tab method makes the 55 fps come back.

...my bad...misread...thought you had a 15fps drop!

Have you tried doing a clean install of your GPU's drivers?

Also try disabling AA I have heard of AA causing this exact same issue.

Also disable anisotropic filtering

Yep, total uninstall and clean installs of both normal as beta Nvidia drivers: no result.

I have this issue too. Seems like a bug as alt tabbing out and back will fix it.

@ Zanderat

I too think its a bug, its not a bug that is there a lot it seems but it is there. I really would like to roll back to the great working 1.4 version of Skyrim: less kill-cams and less underwater eyecandy but WAY more stable game ...

I've the exact same problem, thought was my experimentations to get proper shadows who done that... Great, another bug! Just starting the game, though after 6 months bugs like that would have gone away with patchs, but no...

I experience this too. Haven't tried alt+tab trick but I recently discovered for myself fast travel as quick cure for this fps drop.
Fps drop occurs not only going outside but inside too. And of course my rig can handle game in that places where fps drop suddenly started, it continues even looking on the floor, gpu has 99% percent usage too.

I've had this problem since 11/11/11. I even posted about it in a thread the first time I entered whiterun. I was in the Skyrim Nexus chatroom talking to some modders about it, and they seemed to know what causes it. They posted up some .ini tweaks and suddenly I don't have the problem anymore.

I wish I paid enough attention to keep track of what they told me. I just copy+pasted it. There were some entries under [display] that made all the difference.

The good news is you can just google "skyrim interior FPS lag" or something similiar, and you will find untold dozens of .ini tweaks that adjust it.

I will tell you this: The one that did it for me had to do with interior reflections off of objects.

@ Varus

It's not a interior fps lag problem. Indoor scenes are just fine. It's like this: outdoor scene running fine with 55 fps, then going for example into a store or cave. In the store or cave fps is fine at 60 fps. Then going outside again and then suddenly it all runs at 15 fps, this can be in a city but can also be wilderness.

i also get this problems inside houses caves are fine but when i go say from whiterun to the out side world all of a sudden ive got massive lag , a alt & tab fixes it for me but it is a pain in the rear also its so random , sometimes it will happen but some times its fine going in and out of towns ( with loading screens ) other times it seems like white run hasnt been droped from memory so it loads the outside world as well as keeping the white run in memory so causeing the game to fill up the memory to fast , alt and tabing may drop the white run load from memory and keep the game world you are in at the time.

Same issue here. I hope there is a fix for this as it is rather annoying

Oh adding this (in case someone from the BS team is reading this ): this problem is *only* for outdoor scenes. Example: I am outdoors (50 fps), going into a cave or store (60fps), do my thing there, go outside and then fps is 15. BUT, when going inside again, then the fps in the cave/store is back to 60 fps. Going outside again, fps is 15. I can do a fast travel but fps stays 15.

Well it certainly shouldn't be your rig - it's beefier than mine and I have no stuttering or lag!
I have noticed that there is a perceptible drop in fps when exiting certain interiors though, and I've no idea why that should be (Riverwood Trader, for me!) I guess it's any interior-exterior transition for you guys though.

I get the same result, but only when I have the official hi-res texture pack enabled. If I disable it in Data Files I don't get the high video memory usage when I go from interior to exterior. I also tried different drivers (Nvidia) but it had no effect.

Vram is not the issue. If it were, you would see all the time in exteriors. I only get this bug intermittently and only when transitioning from indoors to outdoors. If I never go inside, I don't get the bug.

Did read something about maybe the official High Res Texture Pack is the cause of these massive fps drops. So did run without but no difference: with or without high res texture pack the fps drop when going from in- to outdoor is there a lot.
And indeed like Zanderat says: I too can travel all the time from any outdoor scene (plains, cities, mountains, forests, and so on) and my fps stays normal at 50-60 fps. Only when going indoor and then outdoor again and the massive fps drop is there.

Aye. Avoid the official HD pack at all costs. I had all sorts of problems with it. Even if your system can handle it, I advise against to use it. Instead download an unofficial texture pack mod, you are better off.

I've had this issue time and again and it most certainly is related to the shadow system for the game. Turn your shadows down from ultra to high and there will be no more fps dips like the one you describe OP. It doesn't happen all the time, but it does every so often, so I just turn down my shadows and it's fixed.

Do you get FPS drops in outdoor scenes after a while? Take a look at your RAM usage when this "transition-lag" occurs, and see if you notice it spiking up. You should have a look at your savegame sizes aswell.

Yup, I have the same problem here, bro. Only difference is that it lags both indoor and outdoor.