The recent "all-purpose culprit" as respects Safari issues has been extensions, although your issue's being intermittent suggests otherwise.

It's an easy enough try, though, to open Safari's pref pane, turn all your extensions off in one shot with the switch, and see what happens.

Good luck.

The new Great Equalizer is the SEND button.

In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire