nmi i/o io delay ve 5.1-42 4.15.18-4-pve

I found some similar threads but none with my configuration (many are ZFS-related, which i don't use). Since my upgrade from VE 4.x to VE 5.x and the related Spectre/Meltdown patches, i am seeing i/o delays and NMI messages on my VMs. Config (Proxmox-Host): 4.15.18-4-pve #1 SMP PVE 4.15.18-23...