TEST ONLY - combine recent performance patches

With patch

The new entities_per_dataset setting is set to 100. There are 10,000 nodes on the site.

Run 1:

time vendor/bin/drush ssg -v --uri http://drupal8alt.test
>  [notice] 101 out of 101 total items have been processed. queries: 20957, memory: 390.5 MB, non-peak mem: 388.5 MB

________________________________________________________
Executed in   10.20 secs   fish           external
   usr time    5.87 secs  119.00 micros    5.87 secs
   sys time    0.74 secs  721.00 micros    0.74 secs

Run 2:

time vendor/bin/drush ssg -v --uri http://drupal8alt.test
>  [notice] 101 out of 101 total items have been processed. queries: 10411, memory: 106.5 MB, non-peak mem: 104.5 MB

________________________________________________________
Executed in    6.58 secs   fish           external
   usr time    4.78 secs  114.00 micros    4.78 secs
   sys time    0.40 secs  630.00 micros    0.40 secs

Without the patch but with #3202290: Add performance test script

Run 1:

time vendor/bin/drush ssg -v --uri http://drupal8alt.test
>  [notice] 3773 out of 10001 total items have been processed. queries: 41634, memory: 260.5 MB, non-peak mem: 256.5 MB
>  [notice] 7723 out of 10001 total items have been processed. queries: 43462, memory: 278.5 MB, non-peak mem: 276.5 MB
>  [notice] 10001 out of 10001 total items have been processed. queries: 25081, memory: 278.5 MB, non-peak mem: 272.5 MB

________________________________________________________
Executed in   26.85 secs   fish           external
   usr time   13.35 secs  124.00 micros   13.35 secs
   sys time    1.66 secs  654.00 micros    1.66 secs

Run 2:

time vendor/bin/drush ssg -v --uri http://drupal8alt.test
>  [notice] 3887 out of 10001 total items have been processed. queries: 42851, memory: 264.5 MB, non-peak mem: 262.5 MB
>  [notice] 7760 out of 10001 total items have been processed. queries: 42615, memory: 274.5 MB, non-peak mem: 272.5 MB
>  [notice] 10001 out of 10001 total items have been processed. queries: 24671, memory: 274.5 MB, non-peak mem: 268.5 MB

________________________________________________________
Executed in   26.66 secs   fish           external
   usr time   13.30 secs  129.00 micros   13.30 secs
   sys time    1.55 secs  659.00 micros    1.54 secs

All patches apart from #3202290: Add performance test script are now in dev so going to close this one. Thanks @gbyte.