Hello keldore.
Are you using any startup parameters by any chance?
Regards,
Geez

Hello Mr Geez
Not that I'm aware of.(I'm abit of a vanilla player) I obviously open the game through steam and I close background applications such as Dropbox and Skype.
I turn all the settings I can find to relatively low.
These are my specs if they are of any help to you:
O/S-Windows Vista SP2 32-bit
GRAPHICS CARD-AMD Radeon HD 5500
RAM-2GB
PROCESSOR-AMD Phenom 9450e Quad-Core Processor 2.10GHz

Fare thee well!
Keldore

Hello keldore.
Since it appears you are running minimum spec, please try to lower the settings to lowest possible and report back whether the issue still persists.
Regards,
Geez

I have lowered my video settings to the lowest possible, still persists.
(EDIT - Issue can occur totally at random, not just after the couple hour mark I previously stated previously)

Hello keldore.
We are currently looking into the issue, please be patient as this might take some time to fix due to complexity of the issue.
Regards,
Geez

One non English-peaking player reported the same to me. Started about 3 weeks ago, Win 7 64, Video 710m, Stable branch, any difficulty.

Plays 5 minutes, then model got degraded and fps drops to unplayable.

Hello keldore.
Does the issue still persist for you?
Regards,
Geez

last time it happened was about two weeks ago. It has gone from a frequent to a uncommon occurrence.

I had similar prob... Did get new CPU cooler and i am fine now. Dayz is really heavy on CPU, so it does get hot and slowdown to prevent damage.

you really want to get more ram aka 8gb and a 64bit OS (you can use your 32bit key for a 64bit installation, all you need is a 64 bit dvd)