There is no simple answer to diagnose this problem. This is due to the fact that there are many possible causes.
Unless you're referring to poor FPS (frames per second or user end "lag") in a game, then this problem is unlikely to be directly linked to a bad driver.
That said, the problem could be the result of many things:
- Excessive RAM usage
- Excessive CPU usage
- Faulty hardware
- Malicious software
- Resource intensive applications and/or background processes (Such as continuous antivirus file-system scanning)
If you are positive that the problems only occured after you changed the device drivers, it may be a good idea to use the "Windows System Restore" tool and roll your computer back to a time when it worked fine.
To do the above, do the following:
1. Go to "Start"
2. Go to "Accessories"
3. Go to "System Tools"
4. Click on "System Restore"
5. Follow the on-screen system restore process (self explanatory)
As a matter of course and good practice, I suggest running anti virus software and anti spyware software (such as Windows defender) and also windows defragmenter.
I would also do the following:
1. Go to "Start"
2. Go to "Run"
3. Type "MSCONFIG"
4. Click "OK"
1. Click the Start icon
2. Type "MSCONFIG" into the program search box and press the return key.
Once you can see the MSCONFIG application, click on the "Startup" tab and remove any unnecessary programs. (If you don't know what they are, it's best to either leave them alone or research them first)
If none of the methods above help, I suggest waiting for other answers from other parties.
Often the most effective and efficient resolution to these problems is a re-installation of the operating system and a reformat of the harddrive. You could do this with a recovery CD provided by your computer manufacturer or you can also use the Windows XP/Vista installation disc. This is usually only done as a last resort however.
It's worth noting that If you take your computer to a repair shop, and if the problem isn't obvious to them within a short period of time, they would most likely perform the step mentioned in the paragraph above. Some may also charge you for a new Windows license if you're unable to provide a product-key. (The product-keys are sometimes found on stickers found on PC or the bottom of a notebook)
I hope that helps. :)