Remove all your config.pro/config.sup and .ui files and retry. If it seems to be faster, then the problem is in your custom settings.
If not:
add the config.pro option graphics win32_gdi and see if that improves speed. If so, then you have a graphics card issue. Remove the option and try different graphics card drivers.
Verify that you are using a certified ISV driver for the GPU. These are generally available from the computer manufacturer (Dell). The driver can have an effect on performance.