Windows 7: Slow bootup, slow performance

I have a Dell Latitude E6520 i5-2520 (2.5GHz), 8GB RAM, 7200RPM HDD, Windows 7 Pro x64.
After installation everything seems super ok . Bootup time, working in windows, etc.
Then i decided to start the update (about few hundred megabytes). After the upgrade it seems that everything is somehow..slower. Is it just me or someone had the same issue?

In fact, with the latest updates my system seems to be faster. What exactly is slower.

For the boot time, check Event 100 in the event viewer. Here is how you get to it:

Eventvwr
Applications and Service Logs
Microsoft
Windows
Diagnostics - performance
Operational
Event ID 100

Hi there,

Have you tried checking for more updates to see if this fix's the problem? Or tried rebooting several times.

@whs: I have several computers with different architectures. From i3 to i7. All of them seems to slow down especially in internet explorer. Event 100 is present in my logs :

Error 1/10/2013 9:41:04 AM Diagnostics-Performance 100 Boot Performance Monitoring
Windows has started up:
Boot Duration : 117945ms
IsDegradation : false
Incident Time (UTC) : ‎2013‎-‎01‎-‎10T07:38:17.656000300Z

Got a few errors like this from last instalation (about 1 week ago).
I also tried to disable intel speed step. Still no luck.

@D3LL : Offcourse. Already rebooted a lot of times. Also no update except bing desktop that i usually skip.

What do you mean by its slow? Obviously booting up is slow as you've said. What about when your booted into Windows? What's slow about it?

Most of the time cleaning your system registry seems to help, remove temporary internet files etc. Download CCleaner or RegCure and do a cleanup of your system.

Remember to delete any unused files, remove unused programs etc. After uninstalling programs, deleting files etc make sure you do a registry scan to remove those left-overs from your system, as this will help toward system stability and performance.

That is NOT a good advice. Monkeying with the register is asking for trouble. The rest of your suggestions are OK.

I didn't say snooping in the registry editor, I mentioned using CCleaner to scan for registry issues and cleaning them using that tool.