Patchbox 1.3.3 unusable slow [solved: sd card issue]

i want to use renoise on the rp3b. so i installed the latest patchbox on the sd card.
the installation seems to be ok, but it’s barely usable because everything is slow and sluggish
(i use ssh and vnc. have no monitor/ keyboard for the rp.)
an older version of patchbox was running smoothly on the same board.
but it was too old for renoise. ( 32/64bit ARM based Linux with glibc >= 2.28, 7.1+. For example Debian 10 or newer.)
thanks for any help