Vampire the Masquerade Bloodlines slow loading

I installed Vampire The Masquerade Bloodlines onto my mom's computer. The computer's OS is Windows 7. It worked fine in the beginning and I installed an add on and it didn't work and slowed the game down while it was loading. I uninstalled the add on and the game is still is still slow loading and has started to slow down during game play. Can anyone help me? How can I get the game go as fast as it did before?
 
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