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PoulVantera: Does this happen *every* time you start your runs or is this a single/somewhat rare state? I'm sporting a 4 1/2y old potato Acer with an i5-5200U, 8GB RAM and an eXcuse of a GPU that is a GeForce 840M (2GB VRAM)... That said the game also runs just fine with the onboard Intel HD graphics (4400 I believe, if anyone cares).

On quite rare occasions my runs start in slow-mo too but quickly get back to regular speed once I delve down into the mines. I don't really have an eXplanation for that, I can only assume that depending on how the seed starts out the enormous amount of snow on the summit just above the entrance might cause a slow down since it's a couple thousand piXels that each react with each other.

Unless your hardware is busy doing other (heavy-load) things while you're playing I've really no other idea other than the simulated mountain of snow...
I noticed a slo-mo start too yesterday on the train.
might have been several of these issues:
I alt-tabbed between startup of the game and actually playing and meanwhile too sometimes,
I was running on battery for the first 15 minutes
switched to fullscreen mode but not full resolution when I added the power supply.

once I made it through the portal to the holy mountain everything was running as smooth as expected.

system is a quite old Dell Inspiron 7737 Laptop ( 17 inch 1920 x 1080 multitouch)
which sports an Intel Core i7-4500U with 2GB GeForce GT 750M,
16 GB RAM and a 1TB HDD
JamesM2: Will be watching this thread with interest as I am also having this problem. Even navigating the options menu is excrutiatingly slow.

i7-7700 16GB RAM GE Force GTX 1070 Windows 10 64-bit
Here as well.

Has been working fine for ages (have 30 hours+ in game) then after an update it started running at half frame rate. This isn't when a lot of action is going on - it's the entire time.

Literally, you start the game and the cursor moves slower and I can see the frame rate is 30 instead of 60 in top right corner.

Hopefully will get fixed in another update as it's unplayable now.
Seagull85: Hi, I just got Noita because it looks very interesting. But unfortunately it is running very slowly.

Watch the example:

What can I do?

My system: i5 4670, 32GB Ram, Msi Geforce 970 GTX Gaming 4G, Win 7 64 bit.

Thanks for Help!
I induce slow motion artificially by changing my nvidia profile settings with "nvidiaProfile Inspector." Since you're using an nvidia product, I would imagine you can use the same software to lock an appropriate framerate. (My handicapped framerate is 27 fps. 60 is probably normal.)