--- .circleci/config-2_1.yml	2021-10-18 11:17:08.000000000 +0100
+++ .circleci/config-2_1.yml.MIDRES	2021-10-18 11:20:45.000000000 +0100
@@ -101,45 +101,65 @@
   executor:
     name: java8-executor
     #exec_resource_class: xlarge
-  parallelism: 4
+    exec_resource_class: medium
+  parallelism: 25
 
 j8_small_par_executor: &j8_small_par_executor
   executor:
     name: java8-executor
     #exec_resource_class: xlarge
-  parallelism: 1
+    exec_resource_class: large
+  parallelism: 10
 
 j8_medium_par_executor: &j8_medium_par_executor
   executor:
     name: java8-executor
     #exec_resource_class: xlarge
-  parallelism: 1
+    exec_resource_class: large
+  parallelism: 4
+
+j8_large_par_executor: &j8_large_par_executor
+  executor:
+    name: java8-executor
+    exec_resource_class: large
+  parallelism: 50
+
+j8_very_large_par_executor: &j8_very_large_par_executor
+  executor:
+    name: java8-executor
+    exec_resource_class: xlarge
+  parallelism: 100
 
 j8_seq_executor: &j8_seq_executor
   executor:
     name: java8-executor
     #exec_resource_class: xlarge
+    exec_resource_class: medium
   parallelism: 1 # sequential, single container tests: no parallelism benefits
 
 j8_repeated_utest_executor: &j8_repeated_utest_executor
   executor:
     name: java8-executor
-  parallelism: 4
+    exec_resource_class: medium
+  parallelism: 25
 
 j8_repeated_dtest_executor: &j8_repeated_dtest_executor
   executor:
     name: java8-executor
-  parallelism: 4
+    exec_resource_class: large
+  parallelism: 25
 
 j8_repeated_upgrade_dtest_executor: &j8_repeated_upgrade_dtest_executor
   executor:
     name: java8-executor
-  parallelism: 4
+    exec_resource_class: xlarge
+  parallelism: 25
 
 j8_repeated_jvm_upgrade_dtest_executor: &j8_repeated_jvm_upgrade_dtest_executor
   executor:
     name: java8-executor
-  parallelism: 4
+    exec_resource_class: large
+  parallelism: 25
 
 with_dtests_jobs: &with_dtest_jobs
   jobs:
@@ -435,7 +455,7 @@
           target: stress-test
 
   j8_dtests-with-vnodes:
-    <<: *j8_par_executor
+    <<: *j8_large_par_executor
     steps:
       - attach_workspace:
           at: /home/cassandra
@@ -449,7 +469,7 @@
           pytest_extra_args: '--use-vnodes --num-tokens=32 --skip-resource-intensive-tests'
 
   j8_dtests-no-vnodes:
-    <<: *j8_par_executor
+    <<: *j8_large_par_executor
     steps:
       - attach_workspace:
           at: /home/cassandra
@@ -463,7 +483,7 @@
           pytest_extra_args: '--skip-resource-intensive-tests'
 
   j8_upgradetests-no-vnodes:
-    <<: *j8_par_executor
+    <<: *j8_very_large_par_executor
     steps:
       - attach_workspace:
           at: /home/cassandra