ok.. little performance question:

is this normal:

I put 1 lightsource into my level. the level is a hollowed block. inside are 50 models ( 1 playfield and 49 rasterblocks on it ). Each model has the SHADOW Flag activated.
The lightsource is a dynamic light, with active CAST flag.
When i make a testrun, the FPS drop down to 10-20..
Why???

Pc.:
AMD Athlon(tm) 64 X2 Dual Core Processor 4400+ 2,30GHz
3GB DD2 Ram
NVidia GeForce 9400GT

How can this be???