Subgraph starting at SuperCollider timed out, jackd

Hello SuperCollider community !

I have a question !

I try to transform my computer into a powerful pedal effect, since 2 months now so a bit new in all of this…

I try to set up everything like said in this page

Sometime when I’m making test jackd crash saying:
subgraph starting at SuperCollider timed out (subgraph_wait_fd=11, status = 0, state = Running, pollret = 0 revents = 0x0)
internal poll failure reading response from client SuperCollider to a xrun event

(each time this error happened was when I was loading a big IR (5.7Mo))

My options:
s.options.memSize = 8192 * 100;
in Jackd:
sr = 48000
blockSize = 128
period/buffer = 2

I’m using a sound card: Focusrite scarlett 2i2
I’m on arch linux with no realtime kernel (but I’ve installed the arch package realtime-privileges)

Can someone explain me what that mean ?

edit: I omit to say that sclang freeze too at this moment,