But this worked for me to speed up the render (to me, it is incomprehensible as to why though)

try to select part of timeline , add effect to it, and render into new sequence of same type. With patch you should see speedup.

Doing the above made no difference for me in speed.

BUT doing the below worked for me almost immediately to speed up the render (to me, it is incomprehensible as to why though). I have to do more tests until I make sure I am not making a mistake.

try to render first exr sequence (from any source) . Set EXR compression to some cpu intensive choice.

Then load this sequence and in rendering dialog only change name of sequence, so it will create new set of images.