[squid-users] worse performance with cache_dir on

[J Webster]

What are some troubleshooting things to look for with squid performance?
I mainly use it to allow users to stream video content but when the 
cache_dir is on it seems to perform worse than when off. When on the video 
pauses to buffer fairly frequently but not when the cahe_dir is off. This 
shouldn't really be the case should it? Or is it the fact that it's 
streaming content that might cause an issue?
My cache_dir was set to cache_dir ufs /home/squidcache 80000 16 256