CUDA is the way to go.
When did “convolution” went bad? 
That is best way to capture an emulation of a hardware to make a real simulation.
Often more detailed then any DSP programming.
Can I use my graphic card that is free instead invest €$£ money on UAD like UAD-2 card?
Yes exactly the point with CUDA.
Will CUDA hog my CPU?
No zero load on CPU.
Why do so less products offer IR except for “Nebula” and Reverbs plugins that type of simulation of hardware example 1176, SSL Buss Compressor and so on?
Because it takes a lot of CPU resources to simulate.
Does that mean it sound bad? No its great, its the future.
So what has that to do with CUDA and the NVIDIA graphic-card?
CUDA let you direct all processing needed to run example “sample convolution of a 1176” to use the graphic cards GPU.
How fast is GPU VS CPU?Extremely powerful and fast especially on making calculations.
Best Regards
Freddie