PMTUDiscovery vs ClampMSS

[Rob Townley]

Currently, i have nodes with PMTUDiscovery =yes and ClampMSS = yes.
When the server does not receive a PMTU request back from one of the
clients even when the packet size is very small (say 164), then it
reverts to TCP.
Should i turn off PMTUDiscovery or should it be ok to leave on?
It takes a very long time to do simple pings (1 second or so), so i
wonder what else i can do?