After a little bit of investigation it seems that the application opens a huge number of udp sockets, but never closes them. After streaming about 10 minutes I have already about 100 open UDP ports. It seems possible that this is responsible for the memory leak and thus the growing cpu load.
I am having the same problem, the CPU load is around 75% in my laptop.
Not only that, but every time I open a browser tab or do something else on the laptop, music stutters badly on my (remote) speakers, even stops for several seconds. As soon as I shut SWYH down, the CPU load goes back to 10%.