Yes, but not much.
Most PC's have a CPU threshold. When the CPU is not in high use, the PC will reduce the amount of power sent to the CPU. This is configured under Window's Power Options as an Advanced setting.
When you have a ton of tabs open, if they are static content, the tabs will be loaded into RAM. If nothing happens, the CPU doesn't need to process any changes in the tabs. The RAM is doing most of the heavy lifting.
IF, however, you have a video, game, or other request running in the other tab, this will require CPU time (possibly NIC time as well). This CPU time corresponds to a demand for more power to be sent to the CPU. The result is that your PC will use more energy to process all the activity in the open tabs.
To conserve energy, a lot of people put their PC into "Energy Saver" mode. This is where the PC will limit the max power sent to the CPU, causing the PC to consume less energy (overall).
· 3 months ago