Windows Search sucks. Plain and simple.
If your desktop/laptop isn't up to the job, you're not likely to be able to do much about it.
FWIW, I don't use it on any of my servers, desktops, laptops, and only one customer insists upon it at which point they're aware of the limitations and bought a new (quad core) PC to cope. I've spent too long trying to get it to behave that I firmly believe altering your filing styles on the PC is a much more efficient way of working.