Dear Alexandros,
as I'm monitoring cpu+mem load on fix+max for weeks while running my jobs,I noted for >1day the 256G VM on fix using ~all of its mem while having aconstant cpu load < 30%. This is after I killed all but 2 of my jobs. My2 jobs are stopped for now by kill -STOP, to be -CONT.
Checking with iotop, there is no IO problem, and adding all mem, no mem problem(also seen by ~10G used for buff).

fix
09102020
top - 18:24:44 up 208 days,  2:29,  1 user,  load average: 7.04, 8.13, 9.21
Tasks: 670 total,   1 running, 665 sleeping,   3 stopped,   1 zombie
%Cpu(s):  8.9 us,  0.8 sy,  0.0 ni, 84.2 id,  5.6 wa,  0.0 hi,  0.4 si,  0.0 st
MiB Mem : 515779.0 total,  15306.1 free, 489885.8 used,  10587.2 buff/cache
MiB Swap: 192512.0 total,  76012.1 free, 116499.9 used.  22543.8 avail Mem 

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND                                                           
 5760 libvirt+  20   0  265.8g 258.9g   7892 S  21.5  51.4   9035:27 qemu-system-x86                                                   
20070 libvirt+  20   0  133.4g  95.9g   8464 S 302.3  19.0  70430:11 qemu-system-x86                                                   
 8475 libvirt+  20   0  129.5g  85.5g   5024 S  19.2  17.0  35409:13 qemu-system-x86                                                   
16254 libvirt+  20   0   21.0g   8.7g   6416 S   8.6   1.7  18042:44 qemu-system-x86                                                   
33780 libvirt+  20   0   20.9g   6.8g   5752 S   8.9   1.3  17161:44 qemu-system-x86                                                   
14947 reczko    20   0 7739632   6.4g   2048 T   0.0   1.3   1047:48 batchman                                                          
26183 libvirt+  20   0   20.9g   4.0g   6408 S  10.9   0.8  19247:54 qemu-system-x86                                                   
 1280 libvirt+  20   0   20.9g   3.6g   7712 S  10.6   0.7   3846:18 qemu-system-x86                                                   
13808 reczko    20   0 7739632 821496   2100 T   0.0   0.2 937:02.68 batchman

(+
258.9
 95.9
 85.5
  8.7
  6.8
  6.4
  4.0
  3.6)
469.79999999999995