Ubuntu 12.04 is sluggish

I have a Lenovo G580 (4GB DDR3, ~500 GB HDD, Intel i3). I installed Ubuntu using the in-Windows installer on my Windows 7. Ubuntu was (and still is) slightly sluggish.

By sluggish I mean, the OS GUI is perfectly responsive, but an App's GUI sometimes just hangs/freezes for a second, while the rest works, but the app itself can't be accessed (happens with Google Chrome mostly, but other applications suffer, too) and it fixes itself after a few seconds.

I recently installed Windows 8 and it appears to be the same.

Another problem I am experiencing is that, when I try to boot it up, from the Windows 8 boot menu, it doesn't work right away. I have to select Ubuntu, and then I need to reboot the laptop (long press the power button on this laptop), which then automatically skips the Windows 8 boot menu and goes to the Ubuntu login screen. Also, it takes a really long while while it loads up and gets to the login screen (at first it's just staring purple/pink for around 20 seconds, and then when the logo and that load indicator appear, it is loading for 2 to 5 minutes).

I really love using linux for development (since I don't have to constantly use git to test it). But, this sluggishness is really getting in the way. :(

That's because the Wubi installation of Ubuntu is not "the real thing". Disk IO is much slower.

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I never understood the appeal of Wubi. Install the OS as an actual OS. Put the .iso on a dvd or flash drive and install it next to your windows install. As it stands now, your Ubuntu is pretty much an app running inside Windows. (I exaggerate a bit here)

Once you've installed Ubuntu properly, you realize that the sluggishness is on the Windows side of things.

It's not normal for you to have to hard power off your computer in order to boot into your Ubuntu installed with Wubi. With Windows 8, the Boot Manager automatically restarts the computer when you select to boot into another OS due to the way that Windows 8 automatically implements 'fast-start'. Fast-start means that Windows will actually hibernate the system session even when you shut down.

On selecting an alternate OS, Windows 8 removes the hibernated image (otherwise the NTFS partition would be locked for mounting) and sets Ubuntu as a one time default, before rebooting.

The fact that you have to hard power off here indicates there are some problems unrelated to Wubi. I would recommend running a file system check (chkdsk /f), checking for BIOS updates, looking for hardware issues.

Also, since you said Windows 8 is also sluggish this points to something more general.

While Wubi is slightly slower than Ubuntu, it's not as slow as many people claim. Having said that, by doing a normal dual boot it will not be using the underlying NTFS file system, so it might solve the problems you are seeing (if not hardware related).

I would also recommend a normal dual boot over Wubi, since there is less chance of file system corruption and data loss.