Here are a couple of causes for slow compiler performance. These are not the only causes.
1) Disable/Uninstall Anti-Virus, Firewall software, and any other application that installs a file system filter driver.
You can use fltmc.exe from a command line to get a list of running File System Filter Drivers on your machine.
Here are some explanations of why these will impact performance:
"Another common cause of poor I/O performance is if a file system filter driver has been installed. A filter driver intercepts requests before they reach the file system, and performs additional processing such as anti-virus checking and encryption. It goes without saying that this can only have a negative impact on I/O performance."
"To understand why a filter driver can slow things down you need to understand that a filter driver basically installs itself between the application and the underlying file system and intercepts nearly every call being made to the underlying I/O subsystem. Most of the time filter drivers are just fine and run with no problems at all. However, what do they do? An antivirus filter driver may have several tasks that it needs to do for each I/O. This may involve looking up information about a process or file when it's being accessed. If the data source associated with this information changes it can change the amount of time that these operations take. The interesting thing is that the timing change may only be a hundred or so extra milliseconds per call to the registry or file system. Under most cases a user would not even notice this. If however you have some aspect of your application needs to make many thousands of calls and they each take 250+ milliseconds vs. 10 milliseconds, all of a sudden the problem compounds. The classic example of this is a VIRUS PROFILE gets uploaded or pushed to servers and all of a sudden the customer starts seeing performance problems because the data set or comparison for the filter driver changes."
2) If you have PATA drives, CRC errors will cause Windows to fall back to a slower DMA mode or PIO mode. CRC errors can be caused by a bad cable or the HDD may be about to fail.
Check IDE port settings in Device Manager.