Dell Inspiron 15R 5537

hello dear,

i have a dell inspiron 15r 5537 windows 8 system, two days ago i format the entire system by deleting all OEM resevered partition of dell and install windows 7. And I install all drivers for windows from this site http://freedriversandsoftware.blogspot.ae/2014/02/dell-inspiron-5537-driver-download.html .Now there is no unknown device in device manager. But the problem is while im formating windows from some where  my system taking more time to boot than usual. and I feel my computer is little bit slower than before. May i knw why its happing..?

I am sure there is no issue in installing windows 7. but I feel  boot mode in inspiron is different. 

there are two mode :

legacy  and uefi mode.

cd/dvd device boot option is only avaliable in legacy mode. So i choose Legacy mode by disabled secure boot mode and install windows 7. After  that I change the boot option to UEFI mode(this was the mode before i begin). But it show error "no boot device found", this is because before i begin my work there is 3 option in UEFI mode  1: windows boot manager , IPV4, IPV6  but now only two option in UEFI mode  windows boot manager is lost.

Help me to bring my system as fast as earlier

Thankss in Advance..