Prusa MMU3 Final Firmware Update Cuts Filament Swap Times by 20 Percent

Prusa Research's final firmware for the MMU3 shaves 10 seconds off every filament swap on average, and on a sufficiently complex print, that adds up to nearly a full workday of print time recovered.

The update delivers a 20% speed improvement to filament changes, dropping from 52 seconds down to roughly 42 seconds per swap, saving up to 9 seconds. Every supported printer benefits immediately: MK4S, MK3.9, MK3.5, and CORE One/One+ users need to flash two firmware files, version 6.5.3 for the printer and version 3.0.4 for the MMU3 unit itself.

Nine seconds sounds like nothing until the math hits. On a complex five-color model, up to 60% of total print time is spent on non-printing tasks like load/unload sequences and wipe towers. A moderately complex five-color print might perform 400 or more filament swaps; shaving 9 seconds off every one saves an hour on a single print. Scale up to a detailed model with 2,200 changes and you're looking at five and a half hours saved. Prusa's own example drives it home harder: a Lighthouse model contains 3,777 filament changes, which means saving 33,993 seconds, or 9.5 hours.

The gains are not from new hardware; they come entirely from more intelligent sequencing. During unloading, while the printer retracts filament from the nozzle, the MMU simultaneously moves the idler from its parked position to a ready stance, just short of engagement. Engaging from the park position normally takes over a second, but pre-staging virtually eliminates that wait. A refined pressure-relief step right before the unload sequence also prevents extruder motor stalls, allowing Prusa to safely increase retraction speed. Prusa notes the published numbers are deliberately conservative: the figures prioritize reliability across the entire user base, though users with a flawless setup can push loading speed up to 200mm/s and save even more time.

There is one quality-of-life addition worth flagging for anyone running single-material multi-color setups. The new "Filament MMU - Preload All" option asks for the filament type only once and applies it to all slots, which is a practical fix for anyone loading five spools of the same material and tapping through confirmation dialogs for each one.

The strategic context behind calling this a "final" update is significant. The MMU3 has been Prusa's workhorse for single-nozzle multi-material printing, and this release is explicitly framed as giving it "one last significant upgrade" before the INDX system takes over. The INDX will bring even better speeds and up to eight toolheads, but Prusa states the MMU3 remains a great choice and will continue to be offered as long as there is interest. The bootloader update bundled in 6.5.3 is part of that transition: Prusa explicitly states that update "creates the necessary foundation for the upcoming INDX upgrade."

One direct consequence of the INDX pivot is that Prusa will not develop a separate MMU3 integration for the CORE One L, and is instead providing instructions and print files that users can use to customize the CORE One+ MMU3 setup themselves. STEP and DXF files will be provided for the adaptation, along with separately sourced larger buffer plates.

Before flashing, run the Configuration Wizard in PrusaSlicer to pull the latest profiles, then confirm the correct PTFE length in the printer menu under Settings, Hardware, MMU, Front PTFE Length. The per-swap time savings vary partly because PTFE tube length differs between printer models, with longer tubes adding hundreds of milliseconds to each loading cycle. Users on the forum have also noted that swapping PrusaSlicer's default T0 filament change code for M701/M702 macros, which initiate ramming to shape the filament tip on exit, produces noticeably cleaner swaps and reduces failed loads, particularly with PETG.