Your video card may not have enough Video Memory or VRAM (which is 2GB on a GT 1030) to render some scenes so it kicks the rendering off to your CPU, this can/will be a major slow down on your render. This slow down is majorly dependent upon the textures and/or bump maps being applied to your models. You can try some tools to optimize your rendering by shrinking the size of some of these textures/bump maps so you can render within your GPUs VRAM thus decreasing your render times significantly with very little to no loss in quality. Even if you can't get your GPU to do your render you may still cut your render time down.
An example of one such tool is Scene Optimizer:
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which you can download here:
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