What operating system are you using, and does it have all updates?
How much memory have you allocated to Photoshop in Preferences > Performance?
What are your Scratch disk arrangements, and how much space is there on the scratch drive?
Does purging the cache restore the memory?
Check the root directory of the Scratch drive for orphaned Photoshop Temp files? I just checked, and I have a couple of files with old dates!
It's normal to use what is available up to the limit. There is the history to keep, for example. Do you see a performance issue?
Agree normal..... Photoshop manages the storage it allocates if it need more it will allocate, Photoshop will return it when you close it done.
Based on my 32 GB of RAM, Photoshop has allocated 20.5 GB (70%) ... I do have a NVIDIA GeForce GTX 660 Graphics Processor, which I have selected to use, but I've never seen that much of a performance boost from using it. Also, I've monitored my CPU usage during Photoshop use, and even with using the graphics processor, my CPU usage spikes to 100% when Photoshop is "working".
I have also found that there is quite a bit of lag in the program. I though that it would be super smooth with all the upgrades I've made to my PC, but it still takes soooo long.
Regarding scratch disks, I have 2 HDD's, and 1 SSD, in addition to my main SSD. My main SSD runs only my OS, and my programs. I am running Windows 10. I am currently not using any of my additional disks as scratch disks. I have to completely reformat my other SSD because I upgraded from that one to my current SSD, and haven't wiped the old stuff off of it yet. My HDD's are file drives, and both are about 50% full.
I am using Photoshop CC v 20161130.r.29 x64.
History States: 50
Cache Levels: 4
Cache Tile Size: 1024K
Also, is anyone has any good blog articles about Photoshop optimization, as well as setting up Photoshop with the best settings, I'd greatly appreciate it. I've been using these programs for YEARS, but I can never get them set up just right.
Photoshop does not do a lot of intensive graphics that will benefit form having a great GPU. Some Feature do require and benefit like 3D, and a few other filters. If you installer some GPU monitoring software and observe it when using Photoshop you can get an Idea of how much Photoshop uses you GPU and get some ideas of how much some of Photoshop features use you GPU.
Photoshop is a resource hungry Application It may want to use a lot of Memory and it will also always use Scratch Disk Space and User Temp Space and Users Application data space. You want all area to perform well. Temp space and Users Application space is normally on you system Disk your Boot boot Disk as is you System Paging Photoshop will also set it to be its Scratch disk. Your System Disk performance is where all things start.
IMO your system should be on SSD Perhaps a Raid of SSD. It must always have lots of Free Space for use. If it does not you system will bog down to a standstill. If you do a lot of Photoshop heavy lifting if you do not have hundreds of GB free on your system disk. You should edit you Photoshop Preference and make sure you system disk is not Photoshop first Scratch Disk. Photoshop will fill it first scratch before in allocates scratch space on its next scratch disk. Photoshop can use a hundreds of GB of scratch space. Do not let Photoshop fill your system disk.