Try reinstalling kaspersky with the latest installer from the site and see if the performance issues continue.
Try to sort the slow PC issue first then the boot order one, one may even fix the other.
I downloaded and installed CCleaner as you mentioned. I did the registry file cleaner. It found 29 issues. Fixed it. How many times do I need to run this? Kaspersky is also scanning the entire system right now. Thanks a lot for your help again.
Update: Did a second check on registry with CCleaner. This time found 14 issues. fixed it.. The third attempt at registry found no more issues. Now checking the files. I will let you know how this works out. Btw, most of the issues were with dll files. Do you think that could have been the problem?