I got my samples at 200, Clamp at 1.5, Caustics off, but still get so much fireflies or noise, whatever you call it:
Small light source, large room = bad for any unoptimized pathtracer like Cycles = extremely slow convergence. 200 samples is really not very much. More samples or heavy scene optimizations needed, which we can’t really comment on without seeing the scene.
A .blender file or a screen shot of your scene setup, information about what type of lights are you using and where they’re placed, etc. will be really helpful if you want an answer.
Since you don’t provide much info about your scene so I can only start guessing!
If it is a fully enclosed seen (an interior scene with 4 walls around) with just on light source outside…then it’s quite difficult for Cycles (as a typical Path Tracer) to provide a noise free solution easily.
Try Increasing you samples.
Use light portals if you are using Environment Light.
One of your issues is your use of sun lamps:
The position of a sun lamp is completely irrelevant, only its rotation matters, as it will always be treated as being infinitely far away. That’s why it makes no sense to have a sun lamp follow your camera into the tunnel, as its light will never get inside - the tunnel walls will simply block it.
Change that lamp to e. g. a point lamp and you should have significantly more light in your tunnel. More light = faster convergence = less noise.
I totally agree @IkariShinji.
Try another type of lamp area,spot or point…
Give you environment a lighter colour and increase the strength…
Try a newer blender version that supports light portals…
Even if you try all these I still believe that Cycles is not the right tool for these type of scenes specially if you’re rendering in CPU
2.75 might help with this - portals!
Set all your bounces to 0 in the render panel, and then increase them as needed. Bump the total up to 1-2 and try the diffuse at 1-2 as well. ITs unlikely that you’ll need more GI bounces than this, and it helps clear up a lot faster.
Change the lamp following the camera to a point lamp as well, renders a lot faster!