diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index cc6b463b0..38d4c9a50 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -121,7 +121,7 @@ jobs:
 
       - name: Unpack repository archive
         run: |
-          tar -x -z -f ${{ needs.build.outputs.archive }}
+          tar --zstd -x -f ${{ needs.build.outputs.archive }}
           ls -lsha
 
       - name: Download code coverage data
diff --git a/.github/workflows/reusable-build.yml b/.github/workflows/reusable-build.yml
index 87a4052d7..f19fa4ad1 100644
--- a/.github/workflows/reusable-build.yml
+++ b/.github/workflows/reusable-build.yml
@@ -88,8 +88,9 @@ jobs:
         working-directory: ${{ github.workspace }}
         run: |
           # Name of the archive must be unique based on the build parameters
-          ARCHIVE=verilator-${{ inputs.sha }}-${{ inputs.os }}-${{ inputs.cc }}-${{ inputs.dev-asan }}-${{ inputs.dev-gcov }}.tar.gz
-          tar --posix -c -z -f $ARCHIVE repo
+          ARCHIVE=verilator-${{ inputs.sha }}-${{ inputs.os }}-${{ inputs.cc }}-${{ inputs.dev-asan }}-${{ inputs.dev-gcov }}.tar.zst
+          # zstd compresses faster than gzip and decompresses far faster in the many downstream test jobs
+          ZSTD_NBTHREADS=0 tar --posix --zstd -c -f $ARCHIVE repo
           echo "archive=$ARCHIVE" >> "$GITHUB_OUTPUT"
 
       - name: Upload repository archive
@@ -97,3 +98,5 @@ jobs:
         with:
           path: ${{ github.workspace }}/${{ steps.create-archive.outputs.archive }}
           name: ${{ steps.create-archive.outputs.archive }}
+          # Archive is already zstd-compressed; skip upload-artifact's zip pass
+          compression-level: 0
diff --git a/.github/workflows/reusable-rtlmeter-build.yml b/.github/workflows/reusable-rtlmeter-build.yml
index b38ed62cf..1c0078207 100644
--- a/.github/workflows/reusable-rtlmeter-build.yml
+++ b/.github/workflows/reusable-rtlmeter-build.yml
@@ -84,8 +84,9 @@ jobs:
         id: create-archive
         run: |
           SHA=$(git -C repo rev-parse HEAD)
-          ARCHIVE=verilator-$SHA-rtlmeter-${{ inputs.runs-on }}-${{ inputs.cc }}.tar.gz
-          tar --posix -c -z -f $ARCHIVE install
+          ARCHIVE=verilator-$SHA-rtlmeter-${{ inputs.runs-on }}-${{ inputs.cc }}.tar.zst
+          # zstd compresses faster than gzip and decompresses far faster in the downstream run jobs
+          ZSTD_NBTHREADS=0 tar --posix --zstd -c -f $ARCHIVE install
           echo "archive=$ARCHIVE" >> $GITHUB_OUTPUT
 
       - name: Upload Verilator installation archive
@@ -94,3 +95,5 @@ jobs:
           path: ${{ steps.create-archive.outputs.archive }}
           name: ${{ steps.create-archive.outputs.archive }}
           overwrite: true
+          # Archive is already zstd-compressed; skip upload-artifact's zip pass
+          compression-level: 0
diff --git a/.github/workflows/reusable-rtlmeter-run.yml b/.github/workflows/reusable-rtlmeter-run.yml
index ab66647db..c4dfbf913 100644
--- a/.github/workflows/reusable-rtlmeter-run.yml
+++ b/.github/workflows/reusable-rtlmeter-run.yml
@@ -101,7 +101,7 @@ jobs:
 
       - name: Unpack Verilator installation archive - new
         run: |
-          tar -x -z -f ${{ inputs.verilator-archive-new }}
+          tar --zstd -x -f ${{ inputs.verilator-archive-new }}
           mv install verilator-new
 
       - name: Compile cases - new
@@ -164,7 +164,7 @@ jobs:
       - name: Unpack Verilator installation archive - old
         if: ${{ inputs.verilator-archive-old != '' }}
         run: |
-          tar -x -z -f ${{ inputs.verilator-archive-old }}
+          tar --zstd -x -f ${{ inputs.verilator-archive-old }}
           mv install verilator-old
 
       - name: Compile cases - old
diff --git a/.github/workflows/reusable-test.yml b/.github/workflows/reusable-test.yml
index ffec26b84..b36134108 100644
--- a/.github/workflows/reusable-test.yml
+++ b/.github/workflows/reusable-test.yml
@@ -63,7 +63,7 @@ jobs:
       - name: Unpack repository archive
         working-directory: ${{ github.workspace }}
         run: |
-          tar -x -z -f ${{ inputs.archive }}
+          tar --zstd -x -f ${{ inputs.archive }}
           ls -lsha
 
       - name: Cache $CCACHE_DIR