To speed up ui vision use a newly installed browser (I use firefox portable) and then disable the images with an extension.
Ui vision is slower than Imacros because imacros used 1 line for each command while ui vision has many more lines for each command and when scrolling through the commands it takes much longer
I have verified that the browser becomes slower and slower as it is used because it continually increases in size, therefore using a new browser just installed (or portable) offers maximum speed