The issue is a glitch in skyrim. Do you have any mods installed (or a modified exe or something)? If so, try disabling them.
A bit of googling ("Skyrim sped up") for you turned up two suggestions:
Found 100% fix of this problem for PC ( you can also see it below in the comments) :
2. Right click on Skyrim --> Go to process
3. Right click process (TESV.exe for me) ------> Ask a correspondence (last function)
4. Remove the tick from CPU 1 -----> Switch back to the game -----> Enjoy
I have the same problem, I heard pressing Ctrl + Prnt Screen slows it back down to normal speeds but I don't know for sure, worth a try though.
I have no idea if these will work, but your problem isn't hardware related (or it's related to your hw configuration, not that you have a bad computer specs); you may try contacting Bethesda support. Good luck!