Every Sunday morning I slice up a big pan of patatos with some chopped onions and fry them up and eat them throughout the day. The part I hate most is the slicing. Is there a quick way to do this?
What you’re looking for is a “food processor” or a “mandoline.”
Isn’t than an instrument? 
How easy are they to clean afterwards? That is also one of my least favorite parts of cooking.
The mandoline is quick to use and to clean. It’s a fixed blade monunted on half of a hole on a flat surface.
I think you misspelled evil there. Yes a mandolin is the most efficient but you will eventually slice off a chunk of your knuckles due to carelessness. It’s just a matter of when, not if.
Have you seen those gadgets for slicing eggs and tomatoes? It’s a set of blades in a hinged lid over a platform. If you cut a potato into thirds or quarters, it will slice those chunks in one stroke.
In 1967, when I worked at Burger Chef, we had a wall-mounted thing that would slice a whole potato into shoestring fries in one stroke. It looked like a modern-day beercan crusher, except it had a grid of blades at the bottom.
They still have them at In 'n Out Burgers. It’s fun to watch your fries go from potato to crispy goodness without being frozen or processed in any way.
I second Shalmanese with the “You will cut yourself.” Nice tools, but evil. very, very sharp, they are.
Get you a Cuisinart, hon. Life-changing, they are.
If you make one lengthwise cut through the middle of the potato, the two pieces will have a flat side on them, which makes it easy to quickly slice them into half-moon shapes.
Not if you use the food guard that comes with it. 'Course, you have to be smart enough to use it. 
Here’s a cheap one. Note the food guard.
Here’s a more expensive one. Again, note the guard.
I have both types and have yet to cut myself because I use the friggin’ food guard!
Hey Chefguy can you get replacement blades for the expensive ones? Someone abused mine and took a chunk out of the blade!
Try here, if you have a Bron.
Or maybe here, if you have a Matfer (which is what I have; don’t care for the Bron).
I have a food processor with a slicing attachment. It’s very fast, very easy and all the parts go into the dishwasher. Plus you can use it for lots of other stuff too.
Fire your potato gun at a harp.
Buy some cans of ready cooked, sliced potatoes.
Providing, of course, you have a can opener.
I think that’s as fast as you’ll get.
chuckle
Or else string your tennis racket with piano wire and work on your serve.
While standing directly under (and just slightly in front of) an idling jet engine, toss said taters upward. Admittedly, the time saved in slicing the taters is lost in gathering the slices afterward, but no solution is perfect.
If you grow your own potatos, just use your mulching lawn mower.
Or you can have kids and when they get to the appropriate age, you can order them to do it.