Hi Walter,
Thanks for the reply.
I have 8GB ram (I will add another 2x4GB stick by the end of the month). 6GB is dedicated to AE.
“Render Multiple Frames Simultaneously” is disabled.
“Also, if you want Ae to preserve interlacing from start to finish, make sure that you are:
1) interpreting the footage with fields
2) rendering with fields”

AE reads the clips as progressive when I click “match source” in the render window. I don’t know what pulldown means but I’d be glad to learn what it is.
EDIT:
I interpreted the footage as “upper line first” and the interlacing is gone which is what I wanted to achieve. But the rendering time hasn’t change.