I wouldn't say I'm obsessed with fast brewing, but there's no doubt that one of the virtues of "simple" brewing is that it tends to be quicker. That's why it always bugs me when I hear people say that they won't/can't brew lagers because they don't have the time and/or can't temp control for long enough.
Of course you do, and of course you can.
Most anything we want to do in brewing can be done (and done well) with the right method. I'm a believer in the idea that the hard part is figuring out what you want - figuring out how to do it can be surprisingly easy once you settle on your desired outcome.
So, this week, let's assume that you want to brew lagers, but that you've convinced yourself (or have been convinced by others) that they take too long or that you can't hold the proper temperature.
What makes a lager a lager?
Well, if you want to get all historical, lager (from the German lagern) literally just refers to beers that were stored, usually in caves, and therefore at cool-ish temperatures (12C or so - it's German, so we're using metric).
Moving into modern lager style characteristics, though, we generally think of these as "clean and clear" beers. Ester and phenol production is low, alcohols are restrained even when the beer has a high ABV, and they're usually brilliantly clear with a nice jewel tone.
Why? Because that's what you get when you make them the way earlier brewers made them. They're low in esters and phenols and feature "cool" alcohols because they were fermented cooler than, for example, summer farmhouse ales. They're brilliantly clear because they've been sitting and precipitating out solids for weeks, or months.
But that doesn't mean that's the only way to get those characteristics. Why don't we just work backwards and see if we can get this done while shaving time off, preferably in simple ways?
Set the Board for Success
First things first: let's make sure you're stacking the deck in your favor here.
Choose a yeast with a reputation for "clean" fermentations. Not all lager yeasts are equally clean (just like not all ale yeasts create a riot of fermentation characters), so read reviews and product descriptions to get something as flavor-neutral as you can. You might even (cover your ears, orthodoxy-lovers) consider the cleaner ale strains in case your temp control "ceiling" is a little on the high side.
Also, pitch big. Esters and phenols are the result of work, and the less your yeast have to work and the sooner they finish fermentation, the less they'll put out detectable flavors. Take the recommended lager yeast pitch rate, and bump it up by about half.
Consider your style, too. If you're concerned about being able to make a fast lager without creating fermentation flavors, go with something that'll cover them up, at least a bit. Doppelbock and Baltic Porter hide a lot more than Helles and Pilsner.
Last, give your yeast plenty of air. This goes to rapidity in moving through the lag/log phases of the yeast life cycle in which the flavors we don't want are produced: the more oxygen there is in your beer at the start, the quicker they'll settle down and stop producing the stuff we're trying to avoid. Esters and phenols are usually a reaction to heat and/or stress. Reducing at least one of those is a good way to get clean beer.
Now that you've given yourself some structural advantages, let's talk process.
A Question of Time
Lagers don't need to chew up a lot of time, either in your fermentation fridge or in your finished-beer fridge (we all have one or three of those, right?). This is probably the second-most-commonly-cited reason I hear for why people don't make lagers: "I don't have the time to brew lagers because I need the space in the fermentation fridge for other beers." Fine - why are you leaving them in there for so long, then?
The things we want to avoid - principally esters, but other compounds as well - are formed (or their precursors are) pretty early in the fermentation process. How early? Well, if it isn't there by the time we finish the lag phase and growth phase, it probably won't ever appear in levels sufficient to be noticeable. That means that if you start cool and stay cool for about 72 hours, you can pull that beer and leave it at any steady room temperature and still avoid the things that make your lager seem like not-a-lager to your palate.
Voila - free space in the fermentation fridge. I mean, don't leave it in a hot garage or anything, but just your normal basement temps (even if they're in the high-sixties Fahrenheit) aren't likely to cause any real trouble for you. Hell, it might even help you avoid incomplete fermentations and/or increase blowoff of things like sulfur, making your beer even cleaner.
"But what about the extended aging process? I might brew it faster, but I still need to age it..."
Why? Get aggressive with the gelatin (or your preferred clarified) and it'll be bright and clear before you know it. I once turned around a Helles in nine days for a 500-entry competition held three weeks from brew day, and it won a silver medal with a 40+ score.
This isn't really about time. Again, if you have it, it helps, but not having it isn't disqualifying.
A Question of Temperature
A much more valid concern is when people tell me they want to brew lagers but don't have any real form of temperature control.
This one is hairier, because there's no "simple" way to set up an evaporation rig. It's not assembling an aircraft engine, but there's no doubt that it's a bit of a pain.
If you can't get your hands on a chest freezer and temp controller (though thanks to the secondary market and falling prices on products like the Inkbird, those are much more affordable now!), and aren't willing to drape t-shirts and towels and set up a fan, I do have at least one solution that takes minimal effort: ice jugs.
Take six one-gallon plastic jugs. Fill with water. Freeze.
Chill your beer down as cold as you can, put it in a large vessel (bathtubs work), and fill with cold, groundwater-temperature water, as high on your fermenter as you can get it. Except for the deepest parts of the deep south, that will give you a starting temperature in the high-50s or lower (even better in winter, but I'm assuming we're thinking "summer" here).
Immediately add three of your ice jugs. Thermal mass is your friend here. You don't want to cool water down - it's far easier to keep water cool. Do this morning and night, cycling your melted jugs back into the freezer and replacing with the others, for three days. After that, just let it slowly come up to whatever temperature you can hold it at using nothing but water replacement (drain the tub, refill with cold water) for another day or two.
If the three-jug method doesn't keep you below 60F, increase your total to eight and add four at a time - if it's too cold, dial it back. But you want to try to maintain a steady temperature for those 72-96 hours.
After that, you're out of that lag/log phase flavor-production window, and just like your temp-controlled colleagues you can pull your beer and hold it at room temperature!
There's nothing magical about brewing lagers. And, for that matter, then recommendations noted here work just fine for ales, too.
Don't let time or temperature be your reason to not make lagers, though - you've got this!
Keep it simple.