It usually happens after many hours (I'd say at least 5+ hours).
Let me try...

However at this point I'm confident the issue is with the new 4.5.x+ JIT on the long run...

Yeah but I'd have expected memory values to rise much faster compared to 4.4 quickly after boot.

After 3 mins...

https://i.ibb.co/3YktFFr/image.png https://i.ibb.co/jzsf6gD/image.png

Not enough differences :(

Try with only 128M of RAM and 128M of VRAM. Even under 64-bit OS JIT has some limits.

Does 32-bit version have same problem?

Configuring as small as possible RAM+VRAM might also help because "real" Amiga side RAM usage becomes less "random".

More test possibilies:

- remove anything "useless" (extra harddrives, untick every checkbox in harddrives panel, uaescsi.device, bsdsocket and so on)

- boot without startup-sequence and leave it running. Still happening?

Seems finally solved after 4.9.1b4 fixes. No more slowdowns or strange freezes.

https://i.ibb.co/PgNY3Hr/image.png

Will report in this thread if I can still reproduce the issue in the future.