I need to create a large '247 x 122 cm' photoshop document at 300 ppi but its running really slow. What should I do?
I need to create a large '247 x 122 cm' photoshop document at 300 ppi
No, you don't. That's roughly 30000 x 14500 pixels.
It's a common myth that everything for print needs to be 300ppi. It most certainly doesn't. In fact, the bigger it is, the lower the ppi requirement - for the simple reason that it will be seen from that much further away.
For this, a much more realistic resolution is 100 ppi or so. That's plenty enough and will look eminently sharp and crisp from a comfortable distance. That's still a big file - bigger than most current DSLRs can produce natively.