Hi,

I have Windows 7 Ultimate in my laptop, and for the past month it is running at 100% CPU all the time, making the machine very slow. When I look at Task Manager, I see that the top 2 processes are lsass.exe and WmiPrvSE.exe, with 35% each.

Any ideas on how to improve performance?

thanks.

"lsass.exe " = A Microsoft Windows file stored in the c:\windows\system32 or c:\winnt\system32 directory that is short for Local Security Authority Subsystem Service and has the file description: LSA shell. This file is responsible for how Microsoft Windows handles security and security related policies, authority domain authentication, and Active Directory management on your computer.

and

"WmiPrvSE.exe" = Windows Management Instrumentation (WMI) is a component of the Microsoft Windows operating system that provides management information and control in an enterprise environment.  By using industry standards, managers can use WMI to query and set information on desktop systems, applications, networks and other enterprise components.  Developers can use WMI to create event monitoring applications that alert users when important incidents occur.  
In earlier versions of Windows, providers were loaded in-process with the Windows Management service (WinMgmt.exe), running under the LocalSystem security account. Failure of a provider caused the entire WMI service to fail; the next request to WMI restarted the service.
Beginning with Windows XP, WMI resides in a shared service host with several other services. To avoid stopping all the services when a provider fails, providers are loaded into a separate host process named Wmiprvse.exe. Multiple instances of Wmiprvse.exe can run at the same time under different accounts: LocalSystem, NetworkService or LocalService. The WMI core WinMgmt.exe is loaded into the shared Local Service host named Svchost.exe.

I believe your system is infected with virus. kindly scan with genuine antivirus software in safe mode