unpacking rar files question.?

This might be a stupid question, but when i unpact certain rar files, some unpack really quickly and some seem to take a awful long time.
Ive just started unpacking 310 to yuma, and this is one thats taking a long time
23. minutes gone and 14 remaining.
Its only 8 files and same size as any other..
The only thing i can add is that it kinda unpacks, then ask’s to replace this file, with the same file then starts again..
Any ideas folks.?
Answer #1
Is it only with 310 to yuma or to all rar files.
I think the uploader wrong packed it or packed it to have more mb to upload
Answer #2
1. WinRar can be told to use different compression methods.
2. Some files compress a lot (e.g. a PSD) and some hardly compress at all (e.g. a JPEG).
3. If you have a rar full of jpegs it doesn’t have to do much work to uncompress (since it didn’t do any to begin with) and so it will extract quickly.
4. If the original uploaded did say a high compression on a lot of compressible files, it will take longer to extract.
5. Upgrading (or adding more) ram makes raring/unraring much much faster
Answer #3
Its all different files to be fair, 310 was really slow, and i had another movie that took around 2 minutes, as opposed to 30 minutes.
I was just curious really, but thanks for the feedback guys..
Answer #4
To make the answer short; highly compressed files take longer to extract. Like the previous answer given, pics dont compress a huge amount thus, dont need a huge amount of decompression. And the thingymajig with replacing files, if that was part of the question if because the files already exist in the destination chosen (at least a file with teh same name)