@kas1e
Yes, the Busy mode is known to be "incompatible" with CPU dockies that also busy loop. CW measures the idle time (which no other tasks used) by busy looping and apparently CPU dockies do the same so they start racing and both use 50% of the CPU. However, the Simple mode should help with that because it sleeps rather that runs.
I will add the menu and iconify gadget at some point.
@Raziel
Try cloning and building
https://github.com/capehill/tequilaIt can probably show which task is using the CPU.