I had a similar problem with a big .zip file (1.4 Gb) which contains almost 200.000 small files. My Ubuntu 13.10 64 bit would have taken over 10 hours. No freezes, the system doesn't really slow down, it is just that the uncompressing is incredibly slow.
I tried the virtual machine solution mentioned above, with Virtualbox and W7 64. Here comes the surprise:
1) at first, I shared the folder to the virtual machine and tried to unzip it there, in the same location (a virtual F: unit in W7) with 7-zip. No luck, same crappy speed which would take forever. 7-zip reported an initial output of 200 Kb/s, but it kept slowing down until I stopped it (less than 100 kb/s and an ETA of 7 hours, but it probably would have slowed down more and taken way longer).
2) then I moved the .zip file to inside the virtual machine's "hard disk drive" (what the vm believes to be a HDD). So the file was not in a shared folder with Ubuntu. Surprise, surprise, it works great, at around 2000 Kb/s output, so it took less than 15 minutes.
3) anecdotally, a 32-bit Windows 7 system (not a virtual machine) with exactly the same hardware took around one hour, with a stable output around 500 kb/s, according to 7-zip. I have no idea how the 32 to 64 bit change affects uncompressing of files, just thought it'd be good to mention to compare.
Ubuntu 13.10 64 bit with ext4, W7 with NTFS both the vm 64bit and the 32 bit normal system. What really bewilders me is the fact that the W7 vm is really using the underlying ext4 file system, because it is a vm, and still achieves those speeds.
I hope some gurus read this and figure this out, this is extremely annoying and intriguing.