diff --git a/.circleci/config.yml b/.circleci/config.yml
index e2ba6e2d0..dd59e8f30 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -921,6 +921,8 @@ jobs:
         default: no
     docker:
       - image: circleci/node:<<parameters.nodejs_version>>
+    # NOTE: Each external test does 3 separate compile&test runs
+    parallelism: 3
     environment:
       TERM: xterm
       COMPILE_ONLY: <<parameters.compile_only>>
diff --git a/test/externalTests/colony.sh b/test/externalTests/colony.sh
index e32385af6..3aaff4413 100755
--- a/test/externalTests/colony.sh
+++ b/test/externalTests/colony.sh
@@ -38,6 +38,10 @@ function colony_test
     local min_optimizer_level=3
     local max_optimizer_level=3
 
+    local selected_optimizer_levels
+    selected_optimizer_levels=$(circleci_select_steps "$(seq "$min_optimizer_level" "$max_optimizer_level")")
+    print_optimizer_levels_or_exit "$selected_optimizer_levels"
+
     setup_solcjs "$DIR" "$SOLJSON"
     download_project "$repo" "$branch" "$DIR"
 
@@ -54,7 +58,7 @@ function colony_test
     replace_version_pragmas
     force_solc_modules "${DIR}/solc"
 
-    for level in $(seq "$min_optimizer_level" "$max_optimizer_level"); do
+    for level in $selected_optimizer_levels; do
         truffle_run_test "$config_file" "${DIR}/solc" "$level" compile_fn test_fn
     done
 }
diff --git a/test/externalTests/common.sh b/test/externalTests/common.sh
index eaa36d899..9d9d1434e 100644
--- a/test/externalTests/common.sh
+++ b/test/externalTests/common.sh
@@ -24,6 +24,15 @@ set -e
 
 CURRENT_EVM_VERSION=london
 
+function print_optimizer_levels_or_exit
+{
+    local selected_levels="$1"
+
+    [[ $selected_levels != "" ]] || { printWarning "No steps to run. Exiting."; exit 0; }
+
+    printLog "Selected optimizer levels: ${selected_levels}"
+}
+
 function verify_input
 {
     if [ ! -f "$1" ]; then
diff --git a/test/externalTests/ens.sh b/test/externalTests/ens.sh
index 2c98a022f..5d0896520 100755
--- a/test/externalTests/ens.sh
+++ b/test/externalTests/ens.sh
@@ -38,6 +38,10 @@ function ens_test
     local min_optimizer_level=1
     local max_optimizer_level=3
 
+    local selected_optimizer_levels
+    selected_optimizer_levels=$(circleci_select_steps "$(seq "$min_optimizer_level" "$max_optimizer_level")")
+    print_optimizer_levels_or_exit "$selected_optimizer_levels"
+
     setup_solcjs "$DIR" "$SOLJSON"
     download_project "$repo" "$branch" "$DIR"
 
@@ -52,7 +56,7 @@ function ens_test
     replace_version_pragmas
     force_solc_modules "${DIR}/solc"
 
-    for level in $(seq "$min_optimizer_level" "$max_optimizer_level"); do
+    for level in $selected_optimizer_levels; do
         truffle_run_test "$config_file" "${DIR}/solc" "$level" compile_fn test_fn
     done
 }
diff --git a/test/externalTests/gnosis-v2.sh b/test/externalTests/gnosis-v2.sh
index d92bcc186..439a3dd91 100755
--- a/test/externalTests/gnosis-v2.sh
+++ b/test/externalTests/gnosis-v2.sh
@@ -39,6 +39,10 @@ function gnosis_safe_test
     local min_optimizer_level=2
     local max_optimizer_level=3
 
+    local selected_optimizer_levels
+    selected_optimizer_levels=$(circleci_select_steps "$(seq "$min_optimizer_level" "$max_optimizer_level")")
+    print_optimizer_levels_or_exit "$selected_optimizer_levels"
+
     setup_solcjs "$DIR" "$SOLJSON"
     download_project "$repo" "$branch" "$DIR"
 
@@ -53,7 +57,7 @@ function gnosis_safe_test
     replace_version_pragmas
     force_solc_modules "${DIR}/solc"
 
-    for level in $(seq "$min_optimizer_level" "$max_optimizer_level"); do
+    for level in $selected_optimizer_levels; do
         truffle_run_test "$config_file" "${DIR}/solc" "$level" compile_fn test_fn
     done
 }
diff --git a/test/externalTests/gnosis.sh b/test/externalTests/gnosis.sh
index b6d9ab0bc..32b76d9c9 100755
--- a/test/externalTests/gnosis.sh
+++ b/test/externalTests/gnosis.sh
@@ -38,6 +38,10 @@ function gnosis_safe_test
     local min_optimizer_level=2
     local max_optimizer_level=3
 
+    local selected_optimizer_levels
+    selected_optimizer_levels=$(circleci_select_steps "$(seq "$min_optimizer_level" "$max_optimizer_level")")
+    print_optimizer_levels_or_exit "$selected_optimizer_levels"
+
     setup_solcjs "$DIR" "$SOLJSON"
     download_project "$repo" "$branch" "$DIR"
 
@@ -51,7 +55,7 @@ function gnosis_safe_test
     replace_version_pragmas
     force_solc_modules "${DIR}/solc"
 
-    for level in $(seq "$min_optimizer_level" "$max_optimizer_level"); do
+    for level in $selected_optimizer_levels; do
         truffle_run_test "$config_file" "${DIR}/solc" "$level" compile_fn test_fn
     done
 }
diff --git a/test/externalTests/zeppelin.sh b/test/externalTests/zeppelin.sh
index 89c3f7c67..a52dc2141 100755
--- a/test/externalTests/zeppelin.sh
+++ b/test/externalTests/zeppelin.sh
@@ -38,6 +38,10 @@ function zeppelin_test
     local min_optimizer_level=1
     local max_optimizer_level=3
 
+    local selected_optimizer_levels
+    selected_optimizer_levels=$(circleci_select_steps "$(seq "$min_optimizer_level" "$max_optimizer_level")")
+    print_optimizer_levels_or_exit "$selected_optimizer_levels"
+
     setup_solcjs "$DIR" "$SOLJSON"
     download_project "$repo" "$branch" "$DIR"
 
@@ -48,7 +52,7 @@ function zeppelin_test
     replace_version_pragmas
     force_solc_modules "${DIR}/solc"
 
-    for level in $(seq "$min_optimizer_level" "$max_optimizer_level"); do
+    for level in $selected_optimizer_levels; do
         truffle_run_test "$config_file" "${DIR}/solc" "$level" compile_fn test_fn
     done
 }