Printer acceleration
This firmware has increased Max Acceleration which makes printer work louder than stock firmware with most slicers' default settings.
Any movement starts at 0 speed and then accelerates to reach target speed. Although that speedup may seem instantaneous, it's in fact not. Changing the acceleration of your printer movements affects how quick the printer can reach the target speed and how soon it has to decelerate in order to go from full speed to 0.
Low acceleration makes movements more smooth and less abrupt, but it also means that printer will only reach the maximum speeds on long straight moves (e.g. travel moves or while printing decent sized boxes). Higher acceleration allows reaching the target max speed on shorter paths, but will inevitably introduce printing artifacts, such as ringing and uneven extrusion (especially on sharp turns). Some of these issues can be mitigated with Input Shaping and Linear advance.
Stock firmware limits the maximum acceleration to safe and tested settings, but as community demand grew, the limits were raised and now you can run your printer much faster. Since max acceleration is not capped to safe and tested stock values, your printer now will reach max requested speed more often even on shorter paths, which in turn might hit you as surprise when stepper drivers will automatically switch to much louder spreadCycle mode.
By default, some slicing software does not control the actual movement acceleration and assumes some default values (which may or may not match the actual firmware acceleration settings). This may also affect the slicer's print time estimation.
In case your slicer does not control the acceleration explicitly, upgrading from stock to this firmware will probably affect print quality. In this case you can do either of the following solutions.
In Control → Motion → Max Acceleration change values to lower safe and tested (2500/2500/100/2000). Don't forget to Control → Store Configuration to save it.
Re-calibrate your printer presets: run max flowrate, Acceleration, Linear Advance and other calibration tests until you're satisfied with the print quality and speed.
Acceleration control in OrcaSlicer:
Acceleration control in UltiMaker Cura:
