I did 
Its huuuuuugggggeeeee & while I didnt see the 20sec freezes like the OP (on a i7 PC with 16GB RAM) I it was definitely sluggish (2 / 3 sec delays) so i suspect a lesser machine would struggle.
there are certainly areas that could be improved (like several places a switch node with 10+ outputs and its following nodes could all be simplified into one function & a switch statement) but i kinda suspect its just down the these shear volume of nodes and wires in one instance.
If you can break these down somewhat, distribute them across multiple machines (probably even separate instances on the same server would help) then start there. Use MQTT to coordinate the signals where things interact.
I suspect its down to the shear qty of nodes so disabling tabs may not help (as they are still present in the flow & in the editor)
