I assume you're already rendering as a separate process?

Also have a search for BCDEDIT and INCREASEUSERVA 3072 to maximise RAM availability for apps in Windows 7 32 bit

http://www.araxis.com/merge/documentation-windows/enabling-3gb-ram-on-32-bit-windows.en

Poser 11 , 180Gb in 8 Runtimes, PaintShop Pro 9
Windows 7 64 bit, Avast AV, Comodo Firewall
Intel Q9550 Quad Core cpu,  16Gb RAM, 250Gb + 250Gb +160Gb HD, GeForce GTX 1060