Borderlands 2 FPS slow-down issue - help please!!!

[techead]

ok, so I have this weird issue where my FPS slows down to 30 (on the dot) when I start shooting things... otherwise its sitting constant on 60 (on the dot). Once I stop moving, it sits at 30 for a couple of seconds then it goes back to 60... :wtf:

Im running 1920x1200 on a i5-2500k on a ATI 6950 @ 900mhz with the latest drivers off www.amd.com

GPU usage is not even flat lining so I dont understand why Im getting these weird slow-downs??

V-sync is on btw, (hence the 60 fps cap)

 

[techead]

pffft... would appear I answered my own question

http://gaming.stackexchange.com/questions/85017/fps-capping-regardless-of-setting-in-options

While it certainly could be an enforced cap by design (dynamic shadows are "expensive"), this sounds like it could be vsync as well.

Basically (and inaccurately), there is a frame which you see, and a frame which is drawn on. When the drawn one is complete, the contents are passed to the screen for you to see while a new frame is drawn.

In the "olden" days, video was drawn line by line at the upper corner and moving to the lower corner and then there was a delay when the "cursor" reset to the upper corner. The reset happens during a "wait state" (aka swap interval, vertical sync command etc) and the frame would be swapped during this very brief window.

vsync ON means wait for this to swap frames. You get FPS capped at the refresh rate of the monitor, a very stable picture, but fast movement feels choppy.

vsync OFF means don't wait. You get FPS capped at the computer's ability to render it, but you get frames being swapped out while the image is partially rendered (aka "tearing"), but fast movement feels smoother.

With vsync on, if you can't meet or exceed the refresh rate, then the hardware has to pause and wait for the next cycle. This means you wait 2 frames-worth of time to swap. In games, this tends to happen in extended bursts because large amounts of staffage, explosions, etc. taxes hardware. The result is the FPS appears to drop from locked 60 to locked 30.

Plenty of psuedo-technical info here, but that's the gist of it.

 

[agentrfr]

lulz

It happened it few times to me too.

 

[techead]

i dont get it though... I mean, I get it, but I never had this issue on Skyrim when playing with v-sync on.

So why does BL2 have it?

 

[oldhat]

i dont get it though... I mean, I get it, but I never had this issue on Skyrim when playing with v-sync on.

So why does BL2 have it?

Most likely because Borderlands 2 is a lot more demanding on hardware than Skyrim. Skyrim runs well even on low-end hardware...