Does resolution effect speed?

[dra6onfire]

I haven't been able to find much info on this in the forums despite graphics being a heavy center of conversation so here goes my simple question:

Will running Dolphin at 640x480 resolution give me any significant increase in speed over 1080p? It seems like it should but I am considering getting a monitor that can display in 1080p and before I invest in that I would like to know if when I get it I will be disappointed in the results speedwise.

Thanks in advance for the input.