[StillBored]

Its that RAM that is the key, you want enough to keep all the source files and intermediate files sitting in cache, so the only disk activity is updating timestamps and flushing the .O files to disk.

I've seen this problem a few times, someone looks at their N core machine with M GB and says, oh look i'm only using 3/4 of M so when I buy the 4xN cores machine I'm going to put M ram in it again. Then everything runs poorly because the disks are getting hammered now that there are another 32 jobs (or whatever) each consuming a GB. Keep adding ram until their is still free RAM during the build. Its going to run faster from ram that waiting for a super speedy disk to read the next c/.o/etc file.