Logic X isn't officially supported on 10.7, so I suspect that has something to do with it. I know it works perfectly fine in 10.8.4. What year model Mac are you using? Are you using Logic 10.0.1? Your sig should be updated with this information.
You may benefit from upgrading to Mountain Lion as it's generally deemed as being more stable than 10.7 Lion without too much difference in CPU/memory overhead. The only thing you'll really lose is support for some applications, 32-bit kernel extensions, etc.