I have a feeling that my pyro sim is running out either ram or vram or maybe both of them, cause I'm getting error open cl -4, but somehow the simulation is still running very slowly, I'm wondering if I should just kill the process, or just let it run to see if magic happens?

Turn off your OpenCL and try again. Your simulation may be too large to fit within the vRam you have. By using CPU only you may yet still achieve success. But monitor your physical ram usage as well. If you exceed physical ram you are out of luck and will have to lower the quality of your simulation or install more physical memory.

If it is still running and both vram and ram ran out, it is probably hitting the swap, hence the slowness.