|"Safari is hell faster than all other browsers"|
Safari is widely considered to be the slowest browser for Windows...
"almost 100% usage & even courser lags."
...and you just proved it.
Does your computer only slow down when Safari is running? Hit ctrl+shift+esc and click processes. Is Safari monopolizing the CPU, or are there any other processes using CPU time as well?
Your could also try Chrome or Opera. They're much better browsers. Even Apple doesn't think Safari for Windows is a good idea:
mATX Beast | LGA2011 i7-3930K @ 4.2GHz | 16GB quad-channel DDR-1866 | GTX 670
240GB SSD+2TB HDD | Asus Rampage IV Gene | Seasonic X560 | Silverstone TJ08-E