I've tested some other kernel versions. In the description below, "fast" means that the NFS clients booted quickly (~20s) whereas "slow" means that the NFS clients booted slowly (~100s).
In all cases, rx-usecs=200, rx-frames=4. Debian versions: v4.18.0-3-amd64: fast (not tested recently) v4.19.0-4 (4.19.28-2): slow Upstream kernel versions built from source: v4.18.0: fast v4.18.20: fast v4.19.31: slow v5.0.3: slow I'm bisecting between v4.18 and v4.19 now, but it's slow going. Mike.
