Referring to this post from the old forum,
Timo noted that Steinberg are looking into the memory consumption issues with Nuendo 4/5 and large track counts. We have already lost two Nuendo seats to PT9 because the editors who do the content cuts and project prep on their MacBookPros can’t load the sessions.
This issue is not going away. Waiting for several things - MacOS 64bit version, more memory in laptops, and whatever else - will not fix the problem. The only times our sessions hit a large rackmount desktop with huge ram installed are during recording because we’re forced into it by Nuendo, and during final mix using PT HD. Many intermediate editing and production steps are done on laptops with 4G of ram and will stay that way for a while. As they upgrade their laptops track counts always increase and libraries always get bigger, so they will never be able to load a large Nuendo session. Remember - if the audio is in the pool, even as an unused library track, it contributes to memory consumption.
Someone from Steinberg please advise on your progress with this issue - it’s not going away and has already crippled two of our Nuendo seats. In addition as folks discover that PT9 is actually usable they won’t go back to Nuendo because of the ubiquity of PT in the US.