Photoshop CC bad performance

have you set up the scratch disk preference?

Yes!

Performance set up. All the scratch disks are selected

is this a laptop? Having only 5GB ram available and a slow internal drive with 500MB files is not going to be fast.

Can you take a SS of the next section in your prefs: Discos de...

Sure! Thanks for helping, btw. It is not a Laptop, it is a desktop. I Know it is a big file, but working on Photoshop CS6 It runs much better (same file in a very similar PC): 

Is one of those drives faster than the other? Right now you have the C drive as primary scratch and it's nearly full which would definitely be slowing things down. Use the arrows on the right to change the order of the scratch drives so that D comes first and then i would also uncheck the C drive from being used. 

After that, restart Ps and see if that's working better.

Yeah, it seems like its working better, but still lagging. My PS is installed on C: could uncheck it cause any issue?

Sorry, I forgot to answer. Both C: and D: are the same drive!

Wow! You have a nice machine there, man! But honestly, I dont think I need that much. I dont play any game haha. Some upgrade would be great, but again, with CS6 and similar machine, it work with no issue at all. I am just trying to understand if that is a set up issue or is just CC2017 that demands more performance than CS6.

Photoshop over-writes the photo file with each edit. In Photoshop, if you apply a brush stroke, and then apply a filter, the original brush-stroke is gone. Even if you use layers, Photoshop treats each new step as a flat image. Lightroom does not. It re-calculates every change you make and generates a new render each time. Because of this, your computer needs more power. 

I see... Thank you, guys! Any suggestion about which hardware to upgrade first?

Don't listen to that guy. I work on files 10-20x larger than yours on a macpro from 2010 and i have no issues at all. The only upgrade i'd suggest, if you're interested, is adding more ram

Thank you! I wil do that! 

My bad I thought this was a Lightroom question. For a minimum boost in photoshop I’d say upgrade your memory (ram) and add a second hard to use as a scratch disk. I recommend buying a cheap SSD (solid state drive) instead of a spinning disk. If you can afford it, for a better upgrade, I’d recommend 2 ssd’s. Make both C and D drives 2 separate SSD’s.

Thank you, Eugene! Yeah, a SSD would be nice! I'll do that as soon as i can! The information about how photoshop works you gave is helpful anyway, I didn't know that. Cheers!

Ram, Yes. But he also needs to clean up hard drive, leaving 1/3 free for temp cache files. I have a desktop mid 2009, and it works with CC2017, but I'm not doing to latest upgrade to 2018 because it will really slow down.
Couple things- please anyone correct me if I'm wrong here- these suggestions are my humble opinions and my experience from running a network of 3 computers for 19 years. Old and new computers , upgrading once every 18 months at least 1 of my computers. (1 PC - fully loaded and newer, 1- desktop Mac, pretty darn old, 1- Mac laptop pro- 5 years old. )
Suggest-
1-don't let PS auto save,
1b) reduce history states to 25
2) maybe attach a fast 1tb hard drive (USB 3) and use that as your scratch drive,
3) clean your main hard drive or double the size (it's way too full for the size files your working on) btw, your computer's hard drive is going to fail sooner rather than later. (I have seen almost every full harddrive crash within 1 month -give or take. ).
4) increase the ram to minimum 16gb-32preferable.
5) is your display running with 300 dpi? If so , change it down to 72. Newer displays render slow.
6) when cropping, are you removing pixels or does the file still retain all pixels? Make sure they go away, then ''save as' to keep original file separate, just in case.
7) none of my business- but can your files be smaller with the same final out put? Stay with 32 or 16 bit? Or using snapshot instead of too many layers? Not sure what type of files your working on, but I often remove or flatten and keep working on new document to keep files under 200mb. I used to think bigger is better, but I was wrong for many of those assumptions.

My oldest computer is a desktop: Mac Pro mid 2009, 32gb RAM, 1TB SSD hard drive-only 25% full with operating system and apps only, attached external 4 TB hard drive-usb 3.0 on expansion bay-for my mobile files. . Decent graphics card- mid grade (not near my computer right now). 3 additional internal hard drives that are NOT my operating system harddrive. All active photo files on internal and external hard drives so PS runs on the main HD without other things in the way. Then I have a raid/nas backup that only backs up when computer is not being used.

Also, follow suggestions on purging all the cache files every other day or so.

Hi! Thank you! I did clean my drive as much as i could and I'm now using my D as my scratch drive, which is over 40% empty. I am an ilustrator, so I usualy work with large files, especialy if I'm working on a big illustration scene. They are not often as big as the one I'm working now, but I'm want to use it as na test to compare with the performance of PS SC6, you know.

Thank you Rudolf! Eartho's assistance was very helpful, but the problem isn't completely solved. I'm gonna test it for the next days and post what i found here!