Operating system: Linux-5.11.6-1-MANJARO-x86_64-with-glibc2.33 64 Bits
Graphics card: AMD VERDE (DRM 2.50.0, 5.11.6-1-MANJARO, LLVM 11.1.0) AMD 4.5 (Core Profile) Mesa 20.3.4
Broken: version: 2.91 - 2.93.0 Alpha, branch: master, commit date: 2021-03-31 13:01, hash: rB23c1e48e19dd
Short description of error
After scrubbing the timeline in the VSE (image sequence + speed control + image) for some time, blender locks up and has to be terminated from the process table. Sometimes it takes several minutes until it locks up. It is unclear if the speed control and image are necessary for the bug to occur or if they just make it occur earlier.
There is no error in the terminal.
In 2.91, every time the timeline passes over the sequence, 0.5 percentage points of RAM are consumed and once the RAM is at 99.2%, the whole system locks up (since I have no swap).
From 2.92 onward, RAM consumption stops at 43% and does not increase further even if scrubbing continues, but still: blender locks up after up to 5 mins of scrubbing.
Exact steps for others to reproduce the error
Open blender with VSE layout,
load an image sequence (HD, openexr),
apply a speed control effect strip (0.85x speed),
add a transparent png and extend it to the length of the image sequence
scrub the timeline until blender locks up