If you find that this fix doesnt change the start up time problem, then it is recommended to keep using this service, as most up-to-date programs perform better with the new .NET Framework Updates.
1) Hold Windows Key +R, and release.
2) In Run command window, type: services.msc
3) search for .NET Framework 4.xxxxx NGEN
4) right click to change properties of that service.
5) Set the service to "Manual", apply settings and reboot
6) If it still is slow, set the service to "disable".
7)If you know it's not the service, set it back to "Automatic"
Most likely you could have a startup program causing the issue
Although this is now off-topic, you can still experiment with windows startup services and startup apps. through MS Configuration Tool:
1) access the Run command window (just like above)
2) Type: MSCONFIG
3) Click on Services or Startup, change and apply settings you assume could be the culprit.
4) If you want to revert everything back to normal, simply access the MSCONFIG tool again (SafeMode is faster)
5) On the first window (1st tab), just click on "Normal" startup, apply and reboot.
Hope this was helpful
Edited by JRM75, 24 October 2011 - 04:17 PM.