thanks for your reply Tim - I've got a 1920x1080 comp @ 25fps, there's 13gig of RAM allocated to AE & it's a 16 bpc project.
I took on board your suggestions of turning colour management off, reducing the colour depth to 8bpc & turned off multi-processing. This all helped greatly so thank you for that. I guess my question now is do I need to turn multiprocessing back on when I do my final render (obviously I'll need to turn my bit depth back to 16) or is there no speed advantage doing this? also, Ive noticed I have no option for audio to go through my Blackmagic device - it now is feed out of my computer output - is this something that is permanent or is it a Blackmagic issue? I ask because the client audio monitoring in my suite comes out of the Blackmagic at the moment,
Regards,
Jon