I can't fix the slowness of my thunderbird email.

I had been using thunderbird email on my pc with windows 8, my computer recently crashed and was unable to fix. I had to purchase a new computer which had windows 8.1, I have been unable to use thunderbird email since. I have tried everything on the site to fix it but as soon as I open it, it freezes and crashes. Help I am not sure what else to do. Thanks.