Before killing any spiders you should think about the big number of insects that is consumed by even a single spider. Without spiders humanity would be plagued with hoards of insects.
All spiders in central Europe are not really dangerous for humans - the vast majority of them can't even bite through human skin. A tennis ball size swelling from a such a spider is definitely a myth. I've handled quite a few spiders and have never been bitten - not even an attempted bite.
You don't have to love them, but please don't kill them.
"the vast majority of them can't even bite through human skin"
That's bullshit. Almost all spider bites can easily bypass a human's skill.
"tennis ball size swelling from a such a spider is definitely a myth"
Again, bullshit. Ever heard of staph infection? It can be caused via a spider bite. (Technically, any sort of puncture to the skin, but spider bites are common enough).
Then again, I probably wouldn't kill the spider, as I'm sure it'll catch a wasp or two around these parts making it worth my while. (I much rather get bit by a spider than stung by a wasp).