In more direct reply to some of your specific questions, check out GAMS-Tk. It is part of a package called GAMS-X I wrote years ago for mathematical modeling using a proprietary optimization software product called GAMS. That's the largest Perl/Tk application I've ever created.

Although the code has gone stale since I left graduate school, you can see several screen shots. It was quite cutting-edge at the time, if I do say so myself ;-)

It uses GIFgraph (now PNGgraph I believe) and Gnuplot for graphics.

As to graphics and first-person shooters, I think Perl/Tk would be inappropriate for that kind of application because (i) the widget set really wasn't designed for that sort of thing and (ii) you would want to write a 1st person shooter game in C or some other language that gives you fast fast fast code. Perl is not that language.

You may also enjoy taking a peak at the Moaning Goat Meter. I use it on my desktop, and it's a very nicely done and unique Perl/Tk application.

And as far as weight (e.g., process size and resource intensity) and speed go, of course it all depends, but in my experience, Perl/Tk is (i) lighter weight and faster (in some cases much faster) than Java but (ii) a heavier weight than VB for small apps (but not really all that heavy after all, so this shouldn't be a deciding factor), with the size appearing to approach that of VB as the size of the app grows, and a touch slower than VB in most areas (though not noticably so). I've never made scientific observations to back up these statements; they should be taken as subjective and based on a limited sample size.