RTL-SDR Power Consumption

Hi, has anyone yet tried to optimize the rtl drivers towards using less energy on the chipset (cpu doesn't matter for my purpose). I just noticed that the r820 tuner gets awful hot when used normally or even when the device is just inserted into the usb port thus supplied with power. I also have multiple E4000 Tuner based dongles, but these do seem to heat up pretty well also. My hackrf stays quite cold compared to that. Are there chipsets known for less power consumption (thus less heat)? I doubt software could really do much about the chip design, but i'm not deep enough into the rtl chipset to judge whether it's more of a software- or hardware-issue. Any ideas on that topic? Thanks!! Best regards, Ricardo