» Wed May 30, 2012 9:41 am Ok, I know there is a ton of info already on here with regards to input lag and framerate drops/spikes in dungoens or other interiors. Even though the framerates sometimes remain quite high, there is also hitching when you move or look around and it feels more like 10 FPS.This is usually experienced in areas with multiple light sources, especially candles, and the shadows they create. Sometimes I could be staring at a blank wall and my framerate would suddenly drop by 20.
The standard responses I see when people ask how to fix this problem is "The shadows are CPU rendered, so decrease the shadows." or "Limit your frames to a number under 60." or "Run in windowed mode."
Limiting my famerate did smooth out my game some, but the lag and framerate drop remained in interiors with multiple light sources. Running in windows mode did nothing for me at all. These solutions may very well work for some people, but if they didn't work for me, then I have to assume there are others. I also tried a bunch of other things, like recreating my ini files, reinstalling my graphics card drivers, etc. to no avail.
As far as shadows go, I usually run mine at 4096 and while decreasing this value to 2048 does raise my framerate in these situations, I also noticed that the framerate drop/lag still existed, and coincided with my GPU usage jumping to 100%. As soon as I looked away from the problem spot ingame, my GPU usage dropped by 10-20%. I decided to do some quick testing by using MSI afterburner to overclock my GTX 480 and testing shadows at 2048 and 4096.
First, I tested shadows at 2048 with the GPU clock at a stock speed of 700 while staring at the floor in one of the Forts.
This room always lags for me, because there are lots of candles and fires.
Result: 52 FPS http://img835.imageshack.us/img835/9394/2048700.jpg
Then, shadows at 2048 with the GPU clock overclocked to a speed of 800.
(note that I have frame limited the game through nvidia inspector to 59 FPS which basically means it was maxed out.)
Result: 59 FPS http://img19.imageshack.us/img19/9366/2048800.jpg
Then, shadows at 4096 with the GPU clock at a stock speed of 700.
Result: 42 FPS http://img692.imageshack.us/img692/7544/4096700.jpg
Finally, shadows at 4096 with the GPU clock overclocked to a speed of 800.
Result: 48 FPS http://img827.imageshack.us/img827/853/4096800.jpg
As you can see, on my system, raising the Graphics card clock and lowering the shadow resolution both gave me a decent framrate boost in these situations. When used in combination, they totally eliminate the lag and hitching. Where as, simply reducing the shadow resolution doesn't give me enough of a framerate boost for smooth gameplay. I could get the framerates higher if I took shadows down to 1024, but they just look horrible at that resolution IMO and I'd much prefer to clock up my GPU a bit.
I didn't post screens for this, but I did also try playing with different levels of CPU overclocking. I have a Phenom 2 x4 965BE. I usually run with an overclock or 3600Mhz (up from stock 3400). But even at a clockspeed of 3900, the framerate didn't increase by more than 1 in the laggy interior locations. This says to me that while on some systems, the CPU may be the limiting factor, this isn't the case for everyone. Especially given the fact that my GPU was pegged at 100% usage during all tests. In case, you are wondering, my GPU memory usage hovered around 1100 MB, far below my memory limit and therefore probably not a factor.
WARNING: Before you even think about overclocking, make sure you know what you are doing. I have a well cooled system, I monitor heat levels carefully and do lengthy stress testing at each clock speed. There are lots of good tutorials on the net to help you overclock safely. Google is your friend.
One other note: During these tests, I was using Skyboost, a mod which can boost framerates in Skyrim by optimizing some code. There is a new alpha for the 1.4 patch that came out very recently. It does indeed increase framerates in some situations, (ie. very busy areas like the stairs in Whiterun) but did nothing for the lighting/shadow related framerate drops I was experiencing. Nonetheless, you guys should definitely try it. I went from about 49 FPS on the Whiterun stairs, to a solid 57 after installing skyboost.
If all this has already been discussed in detail, I apologize for posting redundant info, but I figured maybe it can help people.
My system:
Windows 7 X64
8 gig 1333mhz RAM
AMD Phenom 2 965BE (clocked at 3600Mhz usually)
GTX 480 1536MB (stock 700mhz, now overclocked to 800 for skyrim)
Skyrim is running off a 64 GB SSD. Ultra settings with some tweaks.
Offical Texture pack, SKyrim HD (partial), Realistic water, and a few others.
1920x1080 - 4 x AA - 16 x AF
