How can I create Windows memory test DVD img?

Hi people!
I have been having issues with my Windows 7 computer for some time now. I realized that when I bought it, it was very fast, but now everything is terribly slow. As a result, I wanted to run Windows Diagnostics on memory to establish whether there are any errors that are making my computer slow. After carrying out the test, I would like to create Windows memory test DVD img of the results. How can I go about the test and creation of the image after I get the results? Thanks.
