Firethen i have to say i dont get how my cpu is the bottleneck.
It is and it isn't. Since TF2 uses so little and old multi-core/multi-threading technology, you're bottlenecked by your core/thread speed. Normally, 100% CPU usage is characteristic of a CPU bottleneck, but since TF2 is not made to use every core of modern CPUs in such a manor that won't happen. From the game's perspective, your CPU is completing its instructions as quickly as possible which would make it the bottleneck, but in reality the real bottleneck is the game because the CPU is capable of completing more instructions simultaneously than it is given.
To increase your performance you would have to overclock your CPU or upgrade it to another with a faster architecture either increases your individual core/thread speed.