Some of my projects take 10 minutes to load, with sometimes many synth instruments to load. Many of the songs on my album use the same collection of slow-loading instruments. Is there a way to tell Sonar to keep the instruments that were laboriously loaded for project A, in memory for project B, so it's easier to switch between projects? It seems silly to wait ten minutes every time, especially when it's usually dumping and then re-loading the exact same instruments.

No, instruments cannot be shared that way. Maybe consider installing an SSD. It should speed up synth loads considerably.

scook
No, instruments cannot be shared that way. Maybe consider installing an SSD. It should speed up synth loads considerably.

Or if you have sufficient system memory, you could load the synths into a RAM disk for a lot less than buying an SSD.
 
http://www.pcworld.com/article/260918/how_to_supercharge_your_pc_with_a_ram_disk.html
 

Insufficient RAM may be contributing to the slow load time. Can't say with the information at hand. More information about the the DAW, the synths and memory usage may lead to a better solution.