windows 7 - How to troubleshoot laggy Lenovo L520?

I have an 18-month old Lenovo L520 (model 7859). It is extremely laggy in Windows 7, sometimes lagging up to 10 seconds before responding to a click or keystroke. (There are times when it will go minutes without delay, but the problem is fairly prevalent while using the computer).

It also occasionally produces a BSOD, reporting BUGCODE_USB_DRIVER. There are no external USB devices connected to the system.

Here are some things I have already done to troubleshoot this problem:

• Restored to factory configuration (several times). Problem appears on the machine immediately after installing from Lenovo recovery partition; no third-party software is required to produce the problem other than perhaps some of what comes with the system.


• Removed most of the pre-installed non-Microsoft software. No effect.


• Checked to make sure the BIOS is already newer then version 1.15 and the controller is set to AHCI mode, per this techote: http://support.lenovo.com/en_EG/downloads/detail.page?DocID=HT062964. Unfortunately, although this seemed promising, the BIOS is already in good shape.


• Looked at various system monitoring tools. As far as I can tell, the problem is nearly-constant (or at least, extremely frequent) disk access, but I can't tell what process is causing this access or how to avoid it. Neither RAM nor CPU are constrained.


• Tried running the computer using Ubuntu on a USB key. The problem DOES NOT appear when booted into Ubuntu on a USB key, leading me to strongly believe this is a software problem.

The computer is usable, kind of, but it definitely isn't performing at a level I'd expect from similar hardware. Unfortunately this wasn't reported to me until the system was out of warranty (although the problem has definitely existed from the day we bought the machine), so making it Lenovo's problem wasn't something I could afford to do. I don't have any other computers of exactly the same model to compare with (though I have some that are quite similar, which do not have this problem).

What should I try next?

Answer

It would make sense to address the BUGCODE_USB_DRIVER - BSOD error. It would at least eliminate that from the equation and it may be related to the performance issue.

Suggest going to control panel and uninsatalling all items in USB controllers:
Goto system > device manager then click the plus next to universal serial bus controllers. Right click on each one then select uninstall. After uninstalling all of them reboot and let windows reinstall the usb drivers.