Try the following one at a time to see if they help:

Windows XP Icon Cache

Are you experiencing icon lag, while browsing thru all your Start icons and programs? Do you have a smaller menu delay and your icons need ages to load? No need to give up.

Just delete the hidden file called IconCache.db file from your profile directory (usually /Documents and Settings/Username/Local Settings/Application Data).
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This is an old tweak from Win2k but I do it to any XP machine that access shared folders...

Rename the following reg key:

From:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\explorer\RemoteComputer\NameSpace\{D6277990-4C6A-11CF-8D87-00AA0060F5BF}

To:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\explorer\RemoteComputer\NameSpace\{xxD6277990-4C6A-11CF-8D87-00AA0060F5BF}

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Automatically Refresh File Lists in Explorer

Change the value of UpdateMode in HKLM\System\CurrentControlSet\Control\Update from 01 to 00