Photoshop :: Files Slower In CC - Any Features Can Turn Off

I finally updated from photoshop 7 (ancient, eh) to Photoshop CC recently. My computer uses Windows 7.I noticed that my files seems slower when I was working on it via photoshop CS3 (office machine) compared to photoshop CC:

1) When zooming in with CTRL+, photoshop CC seems to go from a low res to gradually filtering to higher res, compared to photoshop CS3's rather jagged, broken lines to smoother lines. The new feature, was causing my files to slow down, because zooming in and out seems to be taking longer than before. Is this a feature I can turn off?
 
2) I was wondering if photoshop CC being slow is also affected by my file size. The image is 37cm x 142cm at 300 pixel/inch. The file is quite small at 38.8Mb, but I noticed that the document size on the photoshop status bar is 209.7M/552.0M instead. I was wondering if this status bar was a clearer indicator of how slow I could expect the file to be?
 
3) Lastly, er, this might seem a stupid question, but I was wondering if photoshop CC being slow might be just be an indicator of my computer on the overall being slow. I recently replaced a 3 year old desktop drive with separate power plug with a portable harddrive. When my computer is reading into the harddrive it does get slower. Does Photoshop CC automatically read into external hard drives when it is working?