Your question is very vague, however I will attempt to give you a workable answer. To me, it sounds like it could be a few things, but I will say: more often then not when installing a fresh OS, the computer will run slowly. THis happens for a variety of reasons. The main culprit is usually driver related. Please visit your computer manufacturers website for the appropriate drivers for your computer, also make sure to get the appropriate bit (x86 or x64) version driver. If you have an intel processor, you can visit [http://support.intel.com|www.support.intel.com] then visit tools>updates>auto detector. IMEI, chipset, rapid start, rapid storage drivers make a huge difference in the operational speed of your computer.