You can make your backup media and save a Windows 7 backup image so you have a way back, then try Clean Reinstall - Factory OEM Windows 7.
You must unlock all versions in another version using eicfg removal tool
on the ISO before burning Disk, to access Starter for reinstall.
The rule of thumb is that Windows 7 is always instantaneous and fast with a perfect install on adequate hardware. So if following the tutorial steps to get a perfect install doesn't do it then you need to improve the hardware, which is likely weak and the reason it has Starter to begin with.