Giving VMs 13G of memory on OSX runners might degrade performance

[ibuclaw]

Anecdotally, I noticed that FreeBSD VMs on OSX runners took around ten minutes longer to finish when I didn't override the default memory value - around 30 minutes for 13G (1) vs 20 minutes for 8G (1) (2).

So a slightly better benchmark test was ran, and came back with the following results (1) (2).

Memory	1st run	2nd	3rd	4th
8GB	36m 27s	31m 37s	25m 36s	19m 39s
10GB	27m 18s	29m 16s	21m 31s	26m 42s
12GB	33m 44s	38m 25s	59m 18s	41m 06s
13GB	50m 45s	47m 33s	28m 58s	46m 30s

There looks to be some element of randomness here, but at the same time, the 40-50m runs do seem to be unevenly skewed to the higher memory VMs. Needs many more repeated runs though for a pattern to really show.