You would likely be no better off with Windows 7, Windows 8 actually has less running processes than Windows 7, as 8 is designed to work on lower power portable devices where 7 was not.
The real issue is OEM like HP , Acer, SONY etc who put lots of junkware and unwanted software pre-installed on the system. I have seen laptops which works flawlessly once we wipe the hard drive and install Windows using a clean installation media.
Uninstall all resource hog sofwares - especially AV programs like McAfee and Norton ( Usually HP will Pre-install either one of them in their machines ). Your CPU will work better with lower footprint AV programs like "Bitdefender".
( if it is McAfee , you should also run their cleaning tool after normal uninstall - http://download.mcafee.com/products/licensed/cust_support_patches/MCPR.exe )
Edited by Anshad Edavana, 27 April 2014 - 10:51 PM.