I have a triple beam as well, actually it's a quad beam and I'm sure if you look at yours closely you'll see a fourth beam for the sliding weight at the rear.
Had mine for about 25 years, it's not slower than electronic scales. For my work I required some very accurate electronic scales, which I purchased about 15 years ago. Beauty, I thought, never need to fiddle with the triple beam scales again.
I used the electronic scales about four, maybe five times, then gave up on them. Once or twice I looked up a note on a possible adjustment of a chemical amount, by the time I found the note and worked out what I was going to do, the scales had switched off.
Then there is the not quite flat battery syndrome, talk about frustration!
Mick.