Recently Thunderbird has started running very slowly and comes up not responding. I have disabled all add ons and still have the problem. I have run both thunderbird and windows in safe mode and thunderbird runs fantastic. If i run windows normally and thunderbird in safe mode it runs terrible. I am running windows 7. Unfortunately i cant upgrade to 10 yet as i run a program which is having trouble with 10. From my description i take it i will have a problem with windows somehow. Is there a fix