Large .tif and picture files slow computer tremendously

First off, I've had Windows 7 installed for a good few months now, and every time I go into a folder with one or two large .tiff or some other picture file, the whole computer slows down to a crawl, making me wait for anything up to some hours before it'll even show the preview thumbnail (and not letting me do anything else during). Opening these files has been tiring also, as it just means more waiting. It gets so bad that the mouse pointer belatedly jumps when I move it, refusing to go along smoothly.

A good chunk of my education relies heavily on my ability to produce digital art and designs, and I can't well do that when the files are so difficult to open, let alone preview. I've changed the view in folders to only allow the text to appear, and this has helped with the folders loading up. Of course, when I curse over any of the .tif files, that's it - I have to put up with hours of waiting (not even ctrl+alt+del works) or restart with the power button.

Please, I really need help here.

Welcome!

Do you have thumbnails enabled?

Yes, I have thumbnails enabled (show thunbnails instead of icons) in the Visual Effects panel of Performance Options. If I were to disable this, would a preview still show up? If not, I'd have a difficult time discerning what file is what, as I keep many different versions of my works.

Try disabling it. A preview should not show up. I know, you will not want this, but for the purpose of testing and diagnosing, bear with me.

Okay, I tried disabling it and restarted the comp (made some other small aesthetic changes to speed up, too), but the moment I hover the cursor over the same sort of file, it started to crawl again, so had to force restart. I don't know what this thing is trying to do, but when I hover over, or click on it, the little green bar starts to fill up the address, but stops, and that's when I know it won't respond. ... EDIT: Found out something: as long as I don't do anything else while that green bar is filling up, it doesn't halt or freeze. I'll now try to open the file up. ... Further EDIT: Opened the file up in Photoshop fine, but having to do nothing while it gleans info on it is simply not on. Hell, Vista dealt with these files much better, and that's saying something. I'll keep thumbnails off as it seems to help a little. If there's anything else you can think of that could resolve this problem, then please let me know. Either way, thank you very much.

I'm not sure if this will help, but check out this "solution" from MS.
System performance is slow when I view a multipage TIFF file by using Windows Photo Gallery in Windows Vista

You have not shared your system specs, but I'm assuming you're using at least 3GB of RAM, no? It's possible more RAM won't fix your problem, but it can never hurt.
Nor can defragging hard drives

My specs are in my profile. If not, then I must be missing something. Nah, I'm afraid the method didn't work. I have no problems with Windows Photo Viewer tp begin with, but cheers for having a crack at finding something.