Photoshop running so slow and saving large file size

I'm using Photoshop on my Mac pro m2 512gb. My first project of using photoshop has been going well. But this time, whenever I drag thr image layers on top of each other and adjust the size, it shows up "transfrom process" for almost a minute. Same thing happened when I use "select object", it took me a few minutes to complete the operation. When I try to save the file, it al so took me 2-3 minutes and exported a huge size up to 17gb. I don't know what is the problem, can someone help me out please? Thank you in advance.