What tools can I use to diagnose the exact reason for laptop slowness? And how do I use those tools?

Question

I am running Linux Mint 17 on my laptop. When using applications (mainly Web Browsers) the machine freezes for little time periods. The CPU indicates 100% usage at such times, but this only seems to happen when there are other applications running as well.

Due to this reason, I can't decide whether the issue is with not enough RAM or not enough CPU power. For example, can it be that the high memory usage causes memory to be written to swap and that causes the high CPU usage(but in situations that freeze, tools like top and glances show that Firefox is using 100 CPU)?

So what I need to know is how do I diagnose the root cause of the machine freezing? Are there tools to check the root cause of machine slowness?

The reason why I need to know the root cause is because if it is RAM I can add more RAM or try something like zram. But if it CPU I'll have to consider buying a new laptop.

If it matters, my laptop is HP 1000-1205TX Notebook PC with 4 GB RAM.

Answer 1

You can attempt to use tools like htop and sort by CPU usage/RAM usage/CPU time.

sudo apt-get install htop && htop

You can also use iotop to check for any IO related bottleneck,

sudo apt-get install iotop && sudo iotop

or

sudo iotop -P --only

Answer 2

I would start with something as simple as free to rule out the RAM bottleneck. Here's a sample output you would get:

$ free
             total       used       free     shared    buffers     cached
Mem:        895476     851080      44396          0      11008     557828
-/+ buffers/cache:     282244     613232
Swap:            0          0          0

The line that really matters is -/+ buffers/cache: 282244 613232. It means that out of my 895476 KB of memory available in userspace, 282244 KB are used by processes, and 613232 KB are free (this memory is mostly used by kernel for buffers and cache, but can be freed if need be).

If you're constantly low on memory, consider to buy more, though it's not so easy to consume 4 GB with just web browsing. zram will be less of a solution (if at all), since it uses compression to make more RAM available, and compression uses CPU, slowing the system.

Also, since you mention web browsing, I suggest you take a looke at PaleMoon browser. It's a Firefox fork specifically aimed at netbooks and slower computers.