I can only answer for HotkeyNet and Mojo.

HotkeyNet's impact on performance is microscopic. Mojo's impact is a little bigger.

For most users, WoW is bottlenecked more by the graphics card than by the CPU. HotkeyNet and Mojo have no effect on the video card, so in many cases, that they will have no visible effect on performance.

However it's impossible to predict the result on any particular machine because, for example, a machine might be close to needing to page memory and the addition of any program, even a tiny one, could push it over the line and make it start paging a lot.