speed problems on laptop

[Larry Clapp <larry@theclapp.org>]

Hi, all,

I'd like some help diagnosing speed problems on my laptop.

Hardware:

Dell Latitude, 2 GHz cpu, 512 mb ram, 4 GB swap, nVidia vidio card.

History:

Until recently I ran a custom-compiled 2.6.6 on my Dell Latitude, with
a package mix of stable, testing, and unstable.  I also ran VMWare,
and in it, Microsoft Windows 2000.  I had respectable performance.

Every Tuesday I do "apt-get upgrade" to get anything new.  I also, in
Windows, do a "Windows update" via MS's website.

After this past Tuesday's update, my performance went into the toilet.

Symptoms:

- When editing a file in Vim in a gnome-terminal, it takes longer to
  move the cursor from line to line at the top of the screen than at
  the bottom.  Generally scrolling the window takes longer than
  before.  An xterm is faster than a gnome-terminal, but still seems
  slower than before.
- According to Windows Task Manager, Windows under VMWare uses 30% cpu
  more-or-less constantly (which it may or may not have done before;
  not sure), and more often than not 100%.  *Moving the mouse in a
  circle* uses 60-70% cpu.  Most cpu usage in Task Manager is "kernel"
  usage.
- Switching to "full screen mode" under VMWare makes Windows run
  faster.
- Generally X performance seems slower.
- Generally X seems to take a lot of CPU, as reported in 'top'.
- Slooooow kernel compile.  I'm running one now; so far it's taken 50
  minutes.  By contrast, my 1.4 GHz desktop (with, admittedly, twice
  as much ram) compiles a 2.6.6 in ~8 minutes.

Steps taken:

- I assumed something I'd upgraded had caused problems, so I removed
  the 3 patches Windows Update had applied, and rolled back all my
  Debian packages to pre-Jan-1 state.  No change.
- I've re-installed with Debian/testing.  I want to install the nVidia
  driver from nVidia, but it wants a kernel tree to look at, so I'm
  compiling a kernel.
  - After the re-install, I still observe the general X slowness and
    cpu usage, and gnome-terminal slowness.

Hypotheses:

- Hardware problems?  IRQ contention?
- Someone did something stupid in some basic routine in a core library
  (e.g. memset) that makes it run a lot slower than it used to,
  causing a systemic slowdown, including in VMWare.
  - I'd expect a lot more outcry from the Linux and/or Debian
    community in this case, though.
- My laptop is, for reasons of its own, down-stepping its cpu usage,
  via acpi, cpufreq, or similar.
- Something went wonky in my X setup, making it run really slowly or
  in some less-than-optimized state.

Any hints or advice?  Any help appreciated!

-- Larry Clapp