Currently we use two evergreen global expansion variables to limit the amount the number of CPU cores SCons will use in compile tasks. In particular:

num_scons_link_jobs_available: "0.25"
num_scons_unit_cc_jobs_available: "0.75"

We only use 25% of available cores for link jobs and 75% for cc jobs.

I run a patch with those two variables set to 1 and all compile tasks in all variants simply succeeded without issues.

I think that rather than limiting by default the number of cores, we should instead use all cores by default and cap the number of jobs only in the variants that hit Out of memory limit. (e.g. here)