Is it normal that after you install some programs (2 -3) and then you uninstall them computer slows down? Laptop is doing this and I know that it slows down because after I boot up programs take longer to load than usual. After defregmentation everything goes to normal. What can I do?

U can disable some startup programs

Press
Start ---> Run then type in msconfig
*if vista or higher type in search box "msconfig"

Then startup tab and uncheck unwanted apps from loading at startup

Don't be disappoint actually this is because of sevare attack of viruses.If you want to get rid of this problem so you should download Optimo Pro software.It helps in solving your problem.

Programs are conceited, they think any time you uninstall them it just to install the new version, so often they leave traces (settings options registry settings etc.) behind. What I find to be effective when installing something to try it out, is to set a restore point before installing so I can get back to where I was if I don't like them. First run the uninstall then go back in time using system restore you set to get rid of the crap. It's not always practical but safer if your not sure of something. I doubt defragmentation could be the answer as a few installs and uninstalls would not have much effect.