You don't give a lot of detail to work with, but my best stab in the dark is that in X by default the font renderer will sometimes use bitmap fonts (and stretch

You don't give a lot of detail to work with, but my best stab in the dark is that in X by default the font renderer will sometimes use bitmap fonts (and stretch them) when what you really want are vector fonts. You can edit fonts.conf to avoid this, if you like. (Unfortunately, I'm booted into Windows at the moment so I can't copy and paste my configuration.) Or perhaps you've got something else going on entirely. It's hard to say from your post.