How can I determine if Spotlight indexing is running?

Question

I am having occasional severe slowdowns, during which the machine becomes extremely unresponsive. Attempts to switch to a different app can take minutes, even clicking in the menu bar can take more 30 seconds to bring up the menu.
Most of the time this happens, in fact probably all the time, is when I return to the machine after it's been "inactive". My energy saver settings are "never put the computer to sleep when it is inactive" and "put the display to sleep when the computer is inactive for 15 minutes". Screen saver is set to "never".
I believe the cause could be spotlight indexing, but how can I verify that? Occasionally when this happens I've gotten into the terminal window and run "top", but I don't notice anything unusual (but I may not know what to look for). Once, I brought up the spotlight window and it had a line that said something like "indexing in progress". Or perhaps I imagined that, because I haven't seen it since.
I am also using Time Machine, but TM never claims to be doing anything during these slowdowns. TM backs up to a 500G external drive, and I have three drives that I rotate through monthly. At one point I added the top directory on the external drive to Spotlight's privacy list, hoping this would prevent it from indexing the backup. That didn't seem to solve my problem, and in any case the three external drives have different names, and spotlight doesn't seem to remember them. And trying this today spotlight won't let me add the top level folder (Backups.backupdb) but instead forces me to go one layer deeper and add all the folders in that folder (one for each machine I backup).
It would be rather annoying to continually tell spotlight about the backup folders. And I don't even know that spotlight is really the problem.
I've found this thread:
http://discussions.apple.com/thread.jspa?messageID=8977265
but I'd like to verify that spotlight is indeed the cause, and that the solution mentioned there is indeed a proper solution.
Thanks for any help,
Bob H

Answer 1

There are several background operations and actions taking place in the system
and at various levels, too; you may have noticed them in Activity Monitor utility,
and by clicking once to highlight an active one in the list, you can further look into
any one of particular interest to see what else it may have going on.
However, some of these layers of function are rather cryptic to the casual user
who may not get around to learning about their usually hidden reason for being.
You may spot something or another in Activity Monitor's list of All functions, and
depending on how that list is ordered or preferences set to be viewed, more or
less information may be available immediately.
And then, there is the Console utility, where you can see what may have been
going on at or near a specific time; since the reports and logs are time dated.
Sometimes, when my computers (no more than two at a time, are on) seem to
be running something or another, but I haven't a clue exactly what, I will look
into both of these utilities to see why; or what it was busily doing.
In Console, you can sometimes see groupings of messages that repeat and
they can appear to be commands that failed or were ignored by the system;
and it still works just fine, at least for the most part. If you find a list of odd
long log messages that are about the time you hear the machine working, it
may be worth a try to discover what the process is, that is running that long.
{It is possible to force spotlight to re-index, and some other things, too. But
the need to do so should be researched before doing that. A tool such as
OnyX can do more than most users would need, outside of its Automation
selection of most common maintenance chores. Be careful if you use it.}
You may have to check into the functioning of the computer to be sure
the system and hardware are OK.
Good luck & happy computing!