Extreme slowdowns

[urandom]

Hello,

I'm currently trying to play the Overture episode. I've noticed that at some precise moments, I get extreme slowdowns. The framerate drops to around 1 frame per couple of seconds. One such area is the very beginning of the 3rd level, where the character wakes up from the fall. Another one is when I first turn to face the swinging lamp in the boat during the 1st level.

These slowdowns seem to happen regardless of the settings I use. Currently I have set the game to 800x600 with a high shader level and motion blur / dof / bloom. I believe these slowdowns might be related to the game itself, rather than my laptop being slow, for several reasons. First, when I experience such a slowdown, everything is extremely slow. When I press [ESC], the menu appears after a couple of seconds, and the mouse response is not back to normal. If I change to another VT, like the first one, and then back again, the game speed is restored. The same effects that are in place during the swinging lamp scene that caused the slowdown are still in effect, yet the game now runs normal. Finally, on the outdoor level, there are quite a few motion blur / dof effects, but there is no noticeable slowdown.

My system specs are as follows:
Ubuntu Jaunty x86_64
Nvidia driver - 185.18.14

The video card is a GeForce 8400M GS.
RAM - 2 GB.
CPU - Intel Core 2 Duo T9500 @ 2.60

If more information is needed, please let me know.