I flashed Klipper onto the printer at the weekend and it's genuinely a different machine. The stock firmware runs everything on the printer's own little microcontroller, which has to plan motion and drive the steppers at the same time, and it runs out of arithmetic before it runs out of motor. The result is a printer that judders and slows on anything with detail, not because the mechanics can't cope but because the brain can't keep up.
Klipper splits the job. A Raspberry Pi does the heavy maths, planning the whole move sequence in advance, and the printer's board just executes the timed step commands it's handed. The microcontroller stops being the bottleneck because it's no longer thinking, only doing. That one change is the whole trick.
The headline feature is input shaping. It measures the printer's own resonance and cancels the ringing that forces you to print slowly, so you can crank the speed back up without the ghosting and ripples on the surface. I ran the calibration, fed it the numbers, and a benchmark print that used to take an hour came off the bed in a little over half that, looking better. The config is a single text file you can actually read and version-control, which after years of opaque firmware menus feels like a holiday. Same hardware, twice the printer. I should have done it ages ago.