Galiger :
So currently I am running an AMD 9590 and was considering going to the Intel 4790k. Is it worth it? And what kind of performance boost would i get?
It's always worth going from a bigger node (AMD Vishera FX 9590 @ 32nm) to a smaller node (Intel Haswell 4790k @22nm) but I would suggest you to wait a bit as AMD is going to release a new CPU/APU AM4 Platform which will have support for new things like DDR4, NVME SSD, etc.
Currently Intel has 2 platforms which support DDR4 and NVME SSD and those are:
X99 (Enthusiast grade)
Z170
But here's the thing, both the X99 and Z170 platforms are not cost efficient at the moment, therefore it's better to wait for couple of months for AMD to release their new platform and then choose the most Cost and performance efficient platform.
One more thing, all the DDR3 platforms are kind of outdated now so, I wont suggest you to go with 4790k as it's only supported by Z97 platform which is only DDR3 compatible.
So, it's better to wait for a while for AMD and then purchase the best, as AMD's new platform will start a competition with intel's new platforms which always leads to drop in price, thus letting you choose best from both the companies.