It takes a lot of time for unpacking packages (about 10 sec to 20 sec even for small packages), even after a new installation. I am using a Lenovo Ideapad 330.
I don't know whether it's a hardware problem or a software one.
My Ubuntu specs:
Half of the hard disk is empty.
Downloading is done in 15 mins but it takes about 3 to 4 hours for a system update. How can I check what is causing the problem?.
It's most likely a slow hard drive. To figure out what component in your system is slow you can run hperf https://github.com/openlvc/hperf I've used it to find disk bottlenecks on VMWare servers.
When you are running it keep note of what suite causes a noticeable lag in the interface. You can then re-run any individual suites or tests suites to verify that area as the root cause.
Folks were mentioning using top. There are other "better" top like programs. I like htop but there is an even better one called "glances". This will give you a graph of disk/network/cpu IO with colors. https://github.com/nicolargo/glances