Even with 2.5MB of RAM, it's going to be slow. The RAM in a Plus/SE isn't the fastest in the world so it's not going to test 4MB in a few seconds like a modern machine. Try testing it against a 1MB Mac, they take a lot less time.
The lines caused by a capacitor failure will look a lot different than that--think along the lines of really thick vertical white bars, checkerboard patterns, etc. These patterns seem especially common on Classic II's. These lines are strange, not the nice uniform pattern you are observing.
If you think a 2.5MB SE takes forever to test RAM, try a 1MB Lisa or a Toshiba T1200 with 640K. Both of these take well over a minute!
The lines caused by a capacitor failure will look a lot different than that--think along the lines of really thick vertical white bars, checkerboard patterns, etc. These patterns seem especially common on Classic II's. These lines are strange, not the nice uniform pattern you are observing.
If you think a 2.5MB SE takes forever to test RAM, try a 1MB Lisa or a Toshiba T1200 with 640K. Both of these take well over a minute!