Losing Steps - Different firmwares

First, I know that I'm probably losing steps. It's not a slipping belt, slipping pulley, motor current, drivers overheating, etc. I've tested pretty much everything I could and I still get disaligned layers.

I noticed though, that when I printed with Repetier Firmware instead of Marlin the print went better and the printer lost way less steps, as shown here.

I used the same speed setting on both firmwares, and it was pretty slow (130mm/s travel, 60mm/s infill, 200mm/s^2 acceleration, 3mm/s jerk).

Printer went full retard with Repetier Firmware, but it seems this happens when using 3D view on Repetier Host, I'll try disabling it and print again to see if it finishes the print.

The hardware is as follow:
Prusa i3;
Sanguinololu 1.3a with 1284p;
DRV8825 driver from Pololu;
4x 42BYGHW609 from Wantai Motor on the axis;
1x 42BYGHM809 from Wantai Motor on the extruder;
GT2 belts with metal pulleys;
12V 29A PSU.

Anyone has any clue on why this difference happens between the firmwares with no changes to the hardware? Or maybe some way to fix my disalignment problem?

Thanks.

Well, different firmwares have different acceleration algorithms and different handling of the other things (interrupts) to be done in a firmware. I'm pretty sure Teacup firmware does the best you can get out of an ATmega to accelerate linearly, without interruptions.

Another important thing is motor tourque, which is given by the current through the steppers. Many recommend to set this by measuring a voltage on the Pololu, for my part I prefer to raise the current until tourque is sufficient. Because every printer has different tourque demands: [reprap.org]

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Yeah, I already tried everything I could imagine to try and make it stop losing steps. The only thing I didn't yet was change the motors. I even bought new smooth rods and stepper drivers from known good sellers here in my country.

And I'm inclined to think it's the motors.

I fixed Repetier Firmware going full retard by disabling Repetier Host 3D view. The result is a lot less lost steps. I reduced the acceleration and speed a lot too, going at 50mm/s^2 acceleration and 30mm/s max printing speed.

With that config, I was able to print my first print with no lost steps. The other prints I tried after that one lost steps.

So I guess that the acceleration algorithm of Repetier Firmware had better performance on my motors than Marlin's algorithm.

Seems that the lost steps was caused by USB connection. Been printing from SD card and didn't have a single misaligned layer.

Seems that Repetier Firmware had a better grip on lost/corrupted data than Marlin and the print was better over USB, but still with some misalignments. From SD card I had no problems.