I have been using Thunderbird for many years under Windows XP Professional. There were no problems and there was a quick response from the programme. My bank forced me to abandon Window XP. I choose for Windows 8., which I installed on my old computer. I installed Thunderbird and I managed to get my e-mail and address book back, but probably not in the proper way. Thunderbird turned out to be slow in downloading mails and responding to clicks and double cliks. I decided to buy a new computer with Windows 8.1. I installed Thunderbird 31.2.0 and transferred my e-mail and address book. Again Thunderbird turned out to be slow. From your help I found out that I should have used a different way of transferring the data. Therefore I de-installed Thunderbird, made a back-up of the data on a stick, deleted the data. I re-installed Thunderbird and transferred the data in the proper way, but Thunderbird is still slow. The question is: Do I need to change some setting? Or any other actions. The attached document (Thunderbird) contains four print screens. At the top of the four pages from Thunderbird you will find the following text: (reageert niet) = (does not respond). In the first print screen I was moving an e-mail (marked blue) from the Inbox (Postvak In) to the folder Kempen-CvKs (marked blue). The e-mail was not immediately moved and the programme stalled. In the second print screen I double clicked an e-mail to enlarge it. No immediate response and the programme stalled. In the third print screen I clicked on the Inbox (Postvak In). No immediate response and the programme stalled. In the fourth print screen the programme stalled while downloading mail. You can see in the bottom line on the screen. I would like to get some help. Best regards, Roelof Haak PS I could not add a document with the print sceens.