This topic/issue is discussed in depth here: The ongoing USB Conspiracy Theory?
In short: there is a bottleneck in the serial transfer from OctoPrint to the router and a lack of calculation power with 8-bit printer boards when it comes to high resolution routes the printer hotend has to handle.
A quick workaround is to reduce the slicing resolution of the slicer.
I have actually seen this thread already and thought I already was using the
for octoprint. I added dtoverlay=disable-bt to /boot/config.txt an removed console=serial0,115200 from /boot/cmdline.txt.
If possible, I would also like to talk directly to the Board in the Printer without going to USB and back using /dev/ttyAMA0, but i couldn't find good instructions so far. Is there even a way to do it without a level shifter?
I guess in the end ill just be buying a 32 bit board
I think it might be quite common with people adding a BLTouch with an 8-bit Melzi board. It saves a fair bit of memory and is recommended in at least a couple of Teaching Tech YouTube videos from last year. It's certainly commented out in my Marlin 1.1.9, where it saves about 4KB, IIRC.
Wrt memory usage, there are two types of limits: ram and storage. Disabling arc releases some storage space, which is indeed needed if one wants BLTouch to work on base Melzi board (these only have ~128kb of storage).
On topic: have you tried increasing "Maximum resolution" in the slicer? it's been documented by CNC Kitchen: https://www.youtube.com/watch?v=Hvw3DrVAeTA
Also have a look at "Maximum deviation" as it's linked, and WILL override the above one, if needed.