There might be several reasons for the slowness. You haven't
told us about your operating speed, how old the computer is, how much memory you have, who you get your service from. Does this happen on a second e-mail address? Yahoo is a web based e-mail address where as Outlook is a mail program and can do a lot more stuff with it. I use Yahoo mail also but I also use my e-mail address that I have with my server. With yahoo if you are going to send out an e-mail with a photo, the photo comes as a attachment but in outlook it comes as part of the e-mail. Part of this problem could have to do with the security that you have. You can adjust some of it. Also if you have already downloaded this at work you already know that it is free of and adware/Spyware and other virus. so if you send it to you at home you know that you are the sender, go to the tray below and select security and right click it and dis able your security for 5 minutes download and then bring you security back on line. Also click on the tool bar above and select options select cookies and history and delete them, a friend of mine didn't know about this and I checked his computer one day and found that he had over 30,000 cookies and a huge history file. these alone will help to speed up your computer.
Note; My next computer is going to be an IMAC, the graphice are the very best, five years of publishing a news letter and only get to use a mac at my son's house, and I am sold on it.